The US dollar is actually a pretty volatile currency, and there are theories that state it is only a matter of time before it implodes on itself due to the constant moneyprinting of US dollars that have been made.
The US dollar only survives because it is tied to the petrodollar, which ironically makes it dependant on energy to even survive as a currency. Without the petrodollar agreements, the US dollar would have crashed along time ago with the amount of dollar notes that have been printed over the years.
There are also theories that say Colonel Sanders will lead an army of lizardmen to take over the world. But... I'm gonna wait on learning the Anthem of Eleven Herbs and Spices.
The rest of this is a little dry, and way, way tl;dr:
Fiat currency can go wrong, but there's nothing inherently wrong with printing money. The question is how do you balance your supply of currency against the spending needs of consumers, the capacity of your economy to supply goods and services, the capacity for investment to expand the supply of goods and services, and the demand for global reserves. Or, put another way, can you keep your supply of money relatively stable against your supply of things to spend it on?
With a hard money standard the answer is no. While fiat currency lets you define your money supply based on the spending needs of your economy, hard money forces you to define your money supply based on some other, unrelated variable. There's no relationship between the supply of gold or number of kilowatt hours you have and the desired capacity for spending and investment across the economy.
So the U.S. prints a lot of currency because there is an enormous demand for it. Between the domestic need for dollars, as the biggest economy in the world, and the global need for dollars, as the world's reserve currency, you just need a
ton of them. Indeed, there's a good argument that domestically the U.S. dollar is actually
under-supplied right now, and that the country might benefit from just turning on the printing presses for a while.
Think about it like this: We have an economy with $5 in it and a bakery that sells bread for $1 a loaf. But that baker actually has the capacity to make twice as much bread as he does. In a hard money scenario we're stuck. The baker's capacity will go under-utilized. In a fiat money scenario we can print $5 more and introduce it to the economy. Now that consumers have the money to spend, the baker will respond by making more bread and everyone gets wealthier. It gets better, because our baker now has excess capital to spend and can either expand his business (growing the amount of bread in the world) or invest in someone else's (adding, perhaps, butter to our small economy).
Of course we do have to be careful. If we misjudged the situation and the baker actually
didn't have extra capacity we will have doubled the money supply against a static supply of goods and services. We will have $2 circulating per loaf of bread and inflation will quickly set in. In this case we shut off the printing presses and turn on the shredders. Yep,
that happens too, although like printing money it mostly takes place electronically these days. (Most currency in an advanced economy is created and destroyed through national treasury lending, not actually printing physical bills.)
This is the argument for why the U.S. should actually be printing more currency. Those economists believe that we currently have far more capacity to create goods and services than we're using, and that the chief bottleneck is lack of consumer spending power. We could be making much, much more bread if people had the money to buy it with. That the U.S. has excess capacity is pretty well accepted, the main counter-argument is that most of that consumer demand is being drained by high end rent seeking and debt, such as student loans for millennials, so extra money would risk creating a bubble and would likely only fuel debt service rather than additional spending.
It's a difficult problem to solve, but it also illustrates one of the key difference between fiat currency and hard money. Under a fiat currency system you
can have this debate. If new money would create sustainable consumer spending power, as it often does, you have that option.
One of the biggest differences between fiat currency and hard money is that, while both can go wrong, you can't really do anything about the many problems that a hard money standard imposes. If your economy outgrows its money supply... well, you're just kind of stuck. You end up with people using things like counting sticks because there's simply not enough money to spend. Eventually deflation sets in. Worst case scenario you end up with the wild speculation swings of something like Bitcoin, which might be many things but it
certainly is not a functional store of value.
It's no coincidence the world began collectively abandoning hard money right around the Industrial Revolution, when meaningful annual economic growth first began. The gold standard never really worked, people spent millennia working around the fact that they never had enough money to spend. That's why they invented counting sticks. But it didn't really become a huge problem until the annual growth in capacity to supply goods and services took off. Year after year people began inventing new machines, populations began exploding, there was
so much more to spend money on... and the amount of money to spend? Well, that depended on tediously finding little hunks of shiny metal and pulling it out of the ground. It started falling apart pretty quickly.
Another thought experiment: We can radically, radically simplify the situation to say that a healthy economy needs a good ratio of Money Supply (M) / Capacity for Spending and Investment (C). If M grows too fast relative to C we get inflation. But if C grows too fast relative to M we get either stagnation (if that capacity goes unused) or deflation (if those products are actually made). Fiat currency lets us move our M up and down depending on current needs. Hard money does not, it only lets you reduce the money supply. Given that modern economies grow every year, the ability to increase M to keep pace with C is not just useful, it's essential.
There's nothing wrong with printing money. Sometimes what an economy needs most desperately is new capital in the system. It can go wrong, but everything about running a country can go wrong. That's not news. The key is that it is more responsive and less prone to systematic error than a commodity-backed currency. As to the U.S. dollar crashing... no. The dollar survives because the country has an enormous, stable economy and its economic policy has been relatively stable (despite recent political turmoil). Just like the pound, the renminbi and so many other currencies.
There's a reason that every significant economy on Earth uses fiat currency and not a single one has a gold-backed system anymore. It simply works better.