Debunking Popular Economic Myths
There is no official reserve currency and the petrodollar is a myth
Today, we’re going to return to debunking mode.
Since the start of the catastrophic Iranian “excursion,” there has been a marked increase in discussion over a couple of topics that have long been standard in online discourse. You see these everywhere you look.
My usual disclaimer: I am not an economist, nor do I play one on TV. I’ve simply looked into these topics and determined most of the discourse on them to be hokum, even if I don’t claim to know everything about the topic. I know enough to know that much, and I’m tired of all the fearmongering and misinformation online, especially when so many other topics deserve our attention, so I decided to take on this subject as a public service.
The theories start from the following premises:
That the United States dollar has some kind of official status as the world’s reserve currency.
That the dollar’s value is ultimately backed by petroleum in same way it was backed by gold before 1973 (known as the “petrodollar system”, which supposedly supplanted the previous Bretton Woods system.)
That there is an international requirement to price oil in U.S. dollars.
That if oil were ever sold in any other currency besides U.S. dollars, the value of the dollar would plummet and become effectively worthless.
That if the U.S. dollar lost its status as the world’s reserve currency, the United States economy would collapse overnight ushering in a new and even worse Great Depression—mass starvation, homelessness, riots in the streets, fire and brimstone raining from the sky, cats and dogs living together, mass hysteria.
You’ll find these tenets all over on the internet, so much so that it’s now universally believed by the terminally online. No one even questions these premises—they are simply the received wisdom on forums like Reddit and Hacker News.
Yet it turns out that none of these statements are true. They are simply online conspiracy theories that have taken on a life of their own. Yet I constantly hear the most blatant fearmongering coming from various commentators online, even from those that I normally listen to and respect in other instances. In yet another demonstration that Horseshoe Theory is true, these predictably come from political sources on both the extreme right and the extreme left. Well, I guess they agree on something, even the things they agree on are utter nonsense.
Here’s the truth:
There is no single “world reserve currency.” No currency has any such official status.
The value of the dollar is not backed by oil. There is no such thing as the “petrodollar” (there is, however, petrodollar recycling, which is different).
There is no requirement to price oil in dollars, or any particular currency for that matter, and there never has been—not even for Saudi Arabia. In fact, oil transactions can be—and have been—priced in a number of different currencies over the years. Recently, more and more of those transactions are in currencies other than U.S. dollars.
The demand for U.S. dollars is sustained by the sheer size of the U.S. economy and the depth and sophistication of its financial markets, not because oil is priced in it.
The value of global oil transactions pales in comparison to the total volume of global trade. In fact, the relative value of oil to the world economy has been steadily falling for a long time.
The United States is not dependent on foreigners to finance its debt, whether from Gulf states of anywhere else.
If the demand for U.S. dollars falls, there will be macroeconomic effects to be sure, but these are well-known and in-line with the predictions of conventional economic theory. The U.S. economy will not suddenly collapse overnight. In fact, demand for dollars relative to other currencies has already been falling pretty consistently over the years, and is currently at a multi-decade low. There is still plenty of global demand for U.S. Treasuries which are considered a safe asset.
The strength of the United States’ banking and financial institutions, which really did underpin the international value and popularity of the U.S. dollar, are being rapidly undermined by the incompetent Trump administration which will have lasting implications. That should be the real discussion we’re having online, not silly conspiracy theories about the dollar which are easily debunked.
Let’s start with the reserve currency story.
Reserve Currency Status
In fact, no currency on earth has official status as the world’s “reserve currency.” According to Wikipedia, there are currently 180 currencies in use in the world today. Most of the world’s major currencies are held in reserve by various individuals, businesses, pension funds and central banks.
Of those currencies held in reserve, the U.S. dollar is by far the most popular. This is why it’s often referred to as “the world’s reserve currency.” Thus, it becomes a semantic issue whether or not that is accurate; however, I don’t like using the phrase because it implies an official status that simply isn’t there.
So hopefully that makes it a little more clear. No one is making a binary decision to hold their wealth exclusively in U.S. dollars or not. They have many currencies to choose from, and people can and do typically hold a basket of currencies at any one time. It makes sense to do so, given that currencies rise and fall with respect to each other all the time. If your wealth is held exclusively in dollars, and mine is held in Euros, and the dollar falls relative to the Euro you’ve just lost wealth relative to me. There is no global institution enforcing any currency’s reserve status, nor does any country choose to have its currency be a reserve currency, let alone the reserve currency. It’s voluntarily chosen by others. As economist Dean Baker noted in 2013:
Being a reserve currency is not a zero-one proposition. The dollar is the preeminent reserve currency, which means that most of the world’s reserves (@70 percent, last time I checked) are held in dollars. However other currencies like the euro, the British pound, the Japanese yen, and even the Swiss franc are also held as reserves.
In fact, dollar reserve holdings have been declining for quite some time. It’s hardly anything new. According to data freely available to anyone on the internet, foreign exchange reserves of US dollars held by central banks around the world fell from 71% in 1999 to 59% in 2021. Currently, as of this year, the U.S. dollar fell to its lowest share of global reserves since 1994.
Yet, somehow, we’re not living in Mad Max world.
The Petrodollar Myth
The idea that the dollar is “backed” by oil is extremely popular online.
As I understand it, the story goes like this. Back in 1971, the U.S. closed the “gold window”—the convertibility of the dollar directly into gold. Then, in 1973, it permanently severed the link to gold allowing international currencies to “float” freely against one another.
But the dollar needed something else to back it.
At the same time, in the early 1970s the United States went to Saudi Arabia and hatched a secret deal. The Saudis were the world’s largest oil producer. According to the agreement, they would sell their oil exclusively for U.S. dollars. In exchange, the United States would defend Saudi Arabia and global shipping lanes using its military might. In addition, the Saudis pledged to invest the profits from selling oil back into the United States economy. This would allow the United States to run huge and persistent trade and budget deficits, which it would not be able to do otherwise. These deficits would allow the U.S to afford said military spending, along with all the other features of the “American Way of Life™.”
Because the Saudis were the world’s largest oil producer and a key member of OPEC, all other oil producing nations also agreed to sell their oil exclusively for dollars. This created an “artificial” demand for U.S. dollars. Because every country in the world needed to buy oil, every country in the world needed to hold U.S dollars in order to do so. This meant that they needed to hold U.S. dollars in reserve. This is what gave the dollar its status as “the world’s reserve currency.” The dollar is, in effect, “backed” by oil.
Because of this artificial demand for U.S. currency to buy oil, the dollar’s value is highly inflated even the face of persistent trade and budget deficits. This makes American exports uncompetitive, which is the reason behind the deindustrialization of the United States. At the same time, the money flowing into U.S capital markets led to the financialization of the U.S. economy. Yet, despite deindustrialization and deficits, demand for dollars in order to buy oil and the Gulf Oil money flowing back into the United States are single-handedly financing the deficit and keeping the fragile American economy afloat.
If oil were ever sold in anything other than U.S. dollars, the argument goes, this alleged “petrodollar system” would fall apart. When Saddam Hussein priced oil in Euros, that was supposedly an existential threat to the United States. This was the “real” reason for the invasion of Iraq and the subsequent Gulf War (that they won’t tell you about!). With Iran currently selling oil exclusively for Chinese Yuan, these ideas are once again au courant all over the internet.
Furthermore, according to the theory, if the U.S. dollar were ever to lose its reserve currency status, there would a fire sale of U.S. Treasuries and a flight into Yuan and Euros. The United States would no longer be able to fund its budget deficits, because no one will want to buy U.S. debt anymore. Demand for dollars would simply vanish, and the deindustrialized U.S. economy would collapse virtually overnight. Babies will starve, and we’ll be living in a Mad Max movie by next Tuesday, and there’s no way out of this scenario.
That’s how the story goes, anyway. Hopefully I’ve done it justice and told it accurately (if somewhat tongue-in-cheek).
The Reality
But there are several problems with this story.
First, the U.S dollar was already the medium of global trade and the world’s most popular reserve currency long before the alleged secret agreement with the Saudis. In fact, it was even more popular than today when there were no Euros and nobody wanted to hold Chinese currency. I’m not sure exactly when the United States took over as the world’s preeminent reserve currency from the previous claimant—the British Pound sterling—but it was certainly earlier than 1970 (I think it was even before World War 2).
After the nineteenth century, the U.S. settled on a single national currency (the descendant of the “Greenbacks” that funded the Civil War), and established a central bank with the Federal Reserve Act of 1918 (the subject of its own conspiracy theories). These institutional reforms gave stability and reliability to U.S. currency, and from there it rapidly eclipsed the British Pound due to the enormous output of the U.S. economy.
Second, while the U.S. severed the link to gold, under Bretton Woods no other currencies were linked to gold, either. That meant there was no particular reason to flee the dollar for other currencies, nor was there a need to be “backed” by anything in particular, including petroleum, since no other currencies were, either.
Third, the contents of this alleged “secret” agreement with Saudi Arabia have been public knowledge since 2016 due to the Freedom of Information Act. And, guess what? There was no requirement to sell oil for U.S. dollars in it. Let me say that again: there was no provision in this alleged secret agreement to sell oil for U.S. dollars. It’s simply a myth.
In fact, the reason oil is sold in U.S. dollars is because most international transactions are priced in U.S. dollars. It’s simply easier to denominate transactions in a single currency than 180 different ones. This is widely known and common-sense.
In order for a currency to be widely used in international economic transactions, there has to be enough of it, and it needs to be available enough to end users (for example, no capital controls). The fact that dollar denominated deposits can exist outside the United States and outside the control of the Federal Reserve means that it’s easier to get enough dollars for international transactions than any other currency and to hold dollar accounts. This was due to the so-called Eurodollar market.
The Eurodollar market is a complex topic, and I don’t understand it fully. However, it is seen by experts as a much more likely reason for the dollar’s outsized role in international transactions than conspiracy theories about the Saudis and the petrodollar. If you’re a hard-core finance nerd and want to do a deep dive, the excellent podcast Odd Lots did a three-part series about this topic last year. Here’s Adam Tooze writing about it at Chartbook. You can can find a link to the episodes there.
The real reason for the agreement with the Saudis was to ensure a steady supply of oil to the United States. Recall that this was the early 1970’s. The United States hit Hubbert’s Peak in 1970 and fracking hadn’t been invented yet. There were gas lines around the country due to the oil embargo, and the Nixon Administration wanted to ensure a steady supply of oil from the world’s largest oil producer to bring prices down. Its had nothing to do with ensuring sufficient demand for U.S. dollars (which there was already plenty of already).
It’s true that the U.S at the time wanted the Saudis to sell oil in dollars, and did want the money invested in the United States, and held meetings to coordinate these efforts. Prior to this era, oil transactions were roughly 75-25 percent dollars to Pound sterling. After this time, they were nearly all in dollars. Certainly the American government wanted these results, but it would be a wild overstatement to say that this was some sort of grand master plan to “back” the dollar with oil instead of gold. As this article notes,
No, there is no such thing as a petrodollar; there never was. These events did not create an entirely new currency, as the petrodollar term alleges, rather a few new entrants into the wealthy national club were welcomed into the existing and by-then well-established global eurodollar framework.
The existing eurodollar network—offshore bank-centered reserve-less money—merely extended oil producers the same full-range capacities that it had developed over nearly twenty years of massive, unrecognized expansion (qualitative as well as quantitative) before 1973.
But the biggest refutation of the petrodollar theory, in my opinion, is simply the fact that the dollar value of oil transactions pales into insignificance compared to the size of the flows of cross-border trade. To put this into perspective, the value of all oil transactions in an entire year is only one-third of the value of cross-global trade in a single day! There are over 200 official trading days per year, so when the numbers are crunched, the value of oil transactions is virtually insignificant compared to the total yearly volume of world trade. Even if every barrel of oil were priced in something else, it would be vanishingly small portion of the total demand for dollars in international transactions.
So selling oil for dollars did not create some kind of “artificial” demand for U.S. currency; nor is it he reason for the dollar’s (imaginary) world reserve currency status, and it certainly does not underpin the dollar’s value in any meaningful sense.
Defenders of this theory will point out that every country in the world needs oil to run its economy and not, say, bananas. But so what? Why does that matter? If all bananas were priced in dollars, would the dollar now be “backed” by bananas (i.e. the bananadollar)? And besides, the relative importance of oil to global economies—even to the United States economy—has been steadily declining over time. Oil was far more important to the economies of the 1970s and 1980s than it is today, so, by this logic, the petrodollar system should have been unraveling for a long time already. And the United States is now a net oil exporter.
Besides, there’s nothing stopping anyone from exchanging their currency for dollars, making a purchase, and then converting the money back into any currency they choose. In fact, that’s what usually happens: when two non-US currencies are being traded, currency A is first turned into US dollars, and then the US dollars are turned into currency B. Thus, there’s no reason to hold onto lots of U.S. dollars just because some item is priced in dollars. Dollars are freely available for anyone to transact in, so they don’t need to be permanently held in large quantities. Many entities do hold dollars as a matter of convenience, but that’s simply a choice.
While the petrodollar system is a myth, petrodollar recycling is an actual thing. The Gulf States have relatively small populations and sell the world’s most valuable commodity to the rest of the world. This leads to enormous dollar surpluses for them. This is what the term “petrodollar” originally referred to. Much of these excess dollars are invested in the United States, including buying U.S. debt.
But this wasn’t due to any secret agreement—it’s simply because the United States was the only place in the world with capital markets large enough and sophisticated enough to absorb such enormous dollar surpluses at the time. And the idea that we need Gulf money to finance our deficits is silly. If you look at who holds U.S debt, the big ones are Japan and China, with Gulf states holding only a tiny fraction of U.S. debt. The amount they hold is basically insignificant.
All of what I said is available in this video below, from where I got many of the points made in this post. I find his argument rather convincing, much more convincing than the questionable conspiracy theories made by people suffering from acute Dunning-Kruger syndrome on sites like Hacker News and other such places.
The reason the U.S. dollar is the world’s most popular reserve currency has nothing to do with a secret pact with Saudi Arabia, or because people need it to to buy oil. The value of any currency is based on the amount of goods and services available to be purchased with that currency; its relative value compared to other currencies (there is no absolute value); and faith in that country’s political and economic institutions.
…while understanding the value of the enormous and volatile foreign exchange markets remains a work in progress, the standard factors that lead investors to buy and sell currencies have to do with changes in national interest rate, inflation rates, and productivity rates. Also, the Federal Reserve can and does adjust the supply of US dollars, and it can take the demand for the US dollar as a global reserve currency into account in doing so.
I always like to show this image below. It correlates the size of each state’s domestic economy with an equivalent nation-state. Thus we see that, by holding U.S. dollars, you essentially have the equivalent of fifty currencies in a single one. That alone is a pretty significant incentive. Returns on dollar investments and U.S debt have historically been pretty good for investors. We don’t need to invoke conspiracy theories—people and institutions hold dollars because they want to, simple as.
There are a few exceptions to this, however. The Euro is used by a large number of European states including by Europe’s biggest economy, Germany. And, in fact, the Euro has indeed become steadily more popular to hold as a reserve currency. The only other competition would be a single currency from a country with a GDP equivalent to the United States. The only country that fits that bill currently is China. However, as Michael Pettis has repeatedly argued, the Chinese government has bent over backwards and done everything in its power to prevent becoming the world’s reserve currency. Pettis has called reserve currency status an “exorbitant burden.”
One is forced to wonder why, if being the world’s reserve currency supposedly confers such enormous benefits—so much so that the U.S. economy would allegedly collapse overnight without it (according to the pervasive fearmongering online)—then why would the Chinese be working so hard to prevent themselves from becoming the new world’s reserve currency, even as more and more people want to invest in Chinese markets? How do other countries manage to run successful economies without having reserve currency status, and why would the U.S. be incapable of doing the same?
Economist Dean Baker has also previously debunked the petrodollar theory for The Economist and The Financial Times. More recently, he wrote a short post on reserve currencies which I’ve drawn on for many of my points above:
If international demand for dollars falls, the dollar will lose value relative to other currencies. This is well-known and already accounted for in standard economic models. There are even arguments that United States might be better off if the dollar loses it’s unofficial currency “status,” although there is disagreement about that:
If the Dollar Stopped Being the Preeminent Reserve Currency It Would Mean More Jobs and Growth (Center for Economic Policy and Research)
Does the US Benefit When the US Dollar is the Global Reserve Currency? (The Conversable Economist)
In the article above, Baker describes some of the effects this might have on the U.S economy, and why it’s not a cause for panic or fearmongering:
If there was a loss of confidence in the dollar, we are presumably talking about a drop in the ratio of reserves held as dollars. Maybe it would fall to 40 percent, perhaps 30 percent. It is almost impossible it will fall anywhere near zero as long as the United States is in one piece with a functioning economy.
The effect of this loss of confidence would not be to deny the United States the ability to borrow in its own currency. Many countries borrow in their own currency, including countries like Malaysia and Colombia, which are not ordinarily thought of as titans of the world financial system.
Less stable countries typically pay somewhat of risk premium based on the risk of inflation in that country’s currency and the risk of the demise of the country (think Yugoslavia). In several cases this risk premium is negative. For example, the interest rates on Japanese, Swedish, and Danish bonds are all lower than the interest rates on U.S. bonds. These countries do not appear to have suffered from not having the world’s preeminent reserve currency.
Falling demand for U.S. dollars would indeed cause the dollar’s value to fall relative to other global currencies. This means that more dollars would have to be exchanged in order to purchase goods from abroad, possibly leading to higher inflation domestically. However, the other side of this equation will be that American exports will become cheaper. A falling currency will also mean it will be less expensive for tourists to visit the United States, possibly leading to an influx of foreign currency from tourism.
Economic Incompetence
However, even if this were to happen, it’s unlikely that any of these gains would be realized due to the Trump administration’s incompetence.
The Trump administration’s response to this issue has been schizophrenic, to put it mildly. On the one hand, Trump demands a “strong” dollar (because “strong” means good and manly, of course). On the other hand, he also want to increase American exports, which would benefit from a weaker dollar. But since “weakness” is gay and feminine, we can’t have that. It’s worth noting that “strong” and “weak” are not value propositions—they are simply the technical terms used by economists to describe currency fluctuations. It’s certain that Trump himself, as well as many of his officials, are too stupid to understand this.
Additionally, Trump himself has repeatedly claimed that U.S. needs to have to the world’s reserve currency in perpetuity. However, as the Conversable Economist article notes, other Trump administration officials have said the exact opposite—that having the world’s reserve currency is an enormous detriment to the United States. So which is it? Does anybody really know? That’s why it’s doubtful the administration will achieve any of its goals. It doesn’t even seem to agree internally on what those goals are.
Supposedly the way to square this circle is through high tariffs. However, all this did was start a pointless trade war, meaning that U.S. manufacturers will be cut out of any future international trade deals putting them at a disadvantage. Retaliation from other countries will mean counter-tariffs imposed on U.S. manufacturers alone, which will put them at a disadvantage relative to other exporters even if the dollar’s value falls. Tariffs have raised the costs of raw materials imported into the U.S., raising the costs for U.S. manufacturers which will be reflected in higher prices. And, in fact, we’ve not seen the trade deficit reduce at all, even as China’s trade surplus with the rest of the world has grown.
As the Conversable Economist article additionally notes, U.S. manufacturing output has steadily increased despite its supposedly “overvalued” currency. This means that it’s doubtful that a devalued dollar will bring manufacturing jobs back. The fact that U.S. manufacturing employment has declined despite increasing output is probably due to automation and efficiency gains. And manufacturing jobs have continuously declined, not increased, since Trump took office. Tariffs and banning alternative energy in favor of fossil fuels will not bring back the smokestack economy of the 1950s back to the heartland, and that seems to be the only economic plan the administration has (besides deregulation, corruption and looting).
Tourism to the United States is down considerably since Trump took office and launched his crackdown on foreigners. Headlines about random people being swept up and sent to concentration camps have turned people around the world off on visiting what they see as an increasingly authoritarian regime. Even with the World Cup and the Olympics, travel to the U.S. is lower than previously expected, so it’s unlikely that we would benefit from a weaker currency in this arena. According to an analysis by CNN, Trump has directly attacked or threatened 1 out of 13 countries on earth. According to another recent economic analysis, the immigration crackdown has not created more employment opportunities for US-born workers and, in fact, has harmed their prospects, as well as cost an enormous amount of money.
But the most lasting damage has been to the United States’ core institutions. The value of the United States dollar and the ability to finance deficits was always due the fact that the United States had the most trusted financial institutions in the world. No more. Everyone around the world cannot help but notice the drastic decline in the political situation in the United States. The rest of the world is looking on as the U.S. rapidly destroys itself from within due to a radicalized Republican Party which is basically a modern-day fascist party. Whenever Trump speaks, people around the world are able to hear him directly without the pervasive sanewashing performed by domestic U.S. media outlets, and they hear the ramblings of an unhinged madman (quite possibly in the throws of dementia). They have also seen the various clowns, cranks and incompetent sycophants placed in positions of power and authority throughout the federal government. One of the most important tasks for businesses is long-term planning, and for that you need reliability and predictability. But the Trump administration is one of the most volatile and unpredictable regimes on the planet. Not exactly where you want to invest your money. As Dean Baker notes, the U.S. dollar has already fallen in value relative to the Euro, and will likely continue to fall further as long as Trump is in office.
Does the fact that Iran is trading oil in Yuan mean that China is gradually taking its place as the preeminent reserve currency? Not yet, and it’s impossible to know the future, but it would certainly be a long, slow process even if it were. A lot would have to change for that to happen. But the destruction of America’s institutions will have dire economic consequences, even if much of the online conspiracy theories, fearmongering and misinformation has no basis in reality. And the loss of 20 percent of the world’s oil supply will have even more dire consequences on the global economy going forward.
So I hope this rundown has proved useful. So, the next time some commenter, media personality, or influencer starts spouting off about the supposed “petrodollar” and how the United States’ economy will immediately collapse once it’s no longer “the world's reserve currency,” you can now know they’re full of shit and probably shouldn’t be taken seriously about any topic ever again.




You're criticizing a strawman here. I've never seen the version of the argument you're presenting, and given that all of it's assumptions are wrong, perhaps that's not surprising. Yes Joe Bloggs on Reddit is an idiot - but that holds if he's defending the economic orthodoxy just as much.
Reasons for the US being the preeminent global reserve currency vary according to the time and country. In the third world it's really about debt. Existing debts (which should be forgiven - but that's another story), and the ability to get new debt. Lenders put requirements on where they hold their reserves (and not just the governments - the same applies to domestic companies) - which means that a lot of capital in those countries in essence gets recycled into the US economy (super imperialism, as Michael Hudson described it). In SE Asia it's a hang up from the SE Asian financial crisis, and their need to defend their currencies against hot money movements (which is largely in dollars, in part because the US has always been supportive of off shore finance). Yes, the size of the US investible space (which includes stuff like real estate, as well as overpriced stocks) is part of the story, but only part of it.
What happened in the 1970s is that the US did a deal with the gulf that they would recycle their (vast) investible assets in return for the US providing them with military and diplomatic support. The reason for this was that one of the pressures on the US dollar which led to the end of the gold standard (Bretton Woods), was the US trade deficit growing due to the need to buy oil from the gulf (the other factor was the need to finance the Vietnam war). This recycling not only reduce the pressure on the US dollar, but greatly increased the size of the US financial markets. And has been a major factor in various US booms/bubbles (e.g. the current private finance bubble, the recent Silicon Valley VC investments and the AI bubble).
The main reason that there are lots of dollars is because the US exports treasuries to fund its trade deficit. These are what underpin most dollar denominated trades. The US gets two benefits - firstly its a subsidy for imports (reducing their cost), secondly it increases the attractiveness of the US economy as a destination for financial speculation, thus drawing more money into the US and increasing the attractiveness of the dollar and reducing the cost of debt for corporations in the US. A virtuous circle (while it lasts). China and the EU do not want to run trade surpluses, so there just aren't enough of those currencies to support global trade.
Nobody has any idea what would happen if the US dollar stopped being the preeminent currency - and Dean Baker's comments are pretty stupid. It would be a huge shock to the US, and shocks are usually bad. My guess is that you would see a large outflow of money from the US, causing a collapse in real estate, debt, venture capital and stock markets. It wouldn't be pretty.
Is that about to happen? Hard to say. Trust in the US and the dollar system has been significantly weakened in the last 20 years due to a number of factors. These include the US seizing (or freezing) dollar denominated assets of countries and individuals in countries like Venezuela, Iran, Russia, China (and now EU citizens). The whole point of holding money in dollars is that they're supposed to be safe. Part of the perception is also vibes - and certainly the US losing the war against Iran will not help. But the biggest part of this is how well money invested in the US does, and the competence of US financial management. The Obama administration didn't do an amazing job in 2008, but they did a good enough job to preserve US financial hegemony. If in a subsequent crash (caused by, I dunno, the biggest oil shock ever) was to hit, and you saw US incompetence, or worse fraud (managed by, I dunno, Trump) - then that would cause a huge shock and lead people to look for alternatives. If such a crash also led to a loss of competence in the strength of the US as a place to invest (not the same as the strength of the economy) due to a collapse in AI, fraudulent debt markets, etc. Well that would result in people looking for alternatives.
What those alternatives would be I can't say - and if one couldn't be found, it would probably lead to another round of deglobalization and retrenchment.
"The dollar *can't* be the official reserve currency cuz there's no office to stamp the official status! Check mate, nerds!"