I think many of the bitcoin fans reject this. They want to be able to hold (say) 1/1000th of the world's wealth, and be able to keep on holding 1/1000th of the world's wealth as long as they don't spend any of their hoard.
It's like trying to create a financial crisis because you expect to be on the right side of it.
This part is not completely accurate when you consider that money changes hands over time as value is created. (Multipliers)
If the someone produces 1 widget per day (different person each day), and someone else consumes 1 widget per day (and becomes the producer the next day), 1 widget-dollar is needed forever to help move the widgets. If the pattern of production and consumption is more complicated, we need more dollars (debt) to keep track.
The sum total of money needs to be something like the sum total of all current unsettled debt, and it needs to be less than the amount of future production of the debtors, in each's share (or else they will default).
It gets more complicated from there.
That's only if you want the currency to maintain a stable value, neither inflationary nor deflationary.
Alternatively, the currency will have deflation. It's not obvious that that necessarily implies "failing".
Money is supposed to represent value. Not to actually be value. There are new humans arriving in the world all the time. And new resources are being mined from the earth, and created intellectually all the time.
If the money supply does not match these new things then the currency fails.
You can't just do a "currency split" and issue more notes - doing that effectively tells everyone their resources are half as valuable which is clearly wrong - the value of the resources didn't change.
You need to issue more currency so that the sum total of money available is equal to the sum total of value in the world. Any currency that doesn't do that fails.