A money system that works to enable transactions is one where hoarding it doesn't really get you anything. In fact it should cost you to hold a rainy day fund - as any insurance should.
Cryptocurrencies try and pretend they are electronic gold bars. But they are not.
They are ideas with a label on it. Some smart salesman has convinced people that there are only so many ideas with a Bitcoin label and that finite supply will make the price go up. So then people start hoarding them, and transactions for real things start to go down because nobody can get hold of the currency.
So then somebody creates the same idea with a different label, which also has a finite supply...
Classic fallacy of composition. Finite within the scope of the label, but not between labels.
The world's fiat currencies are relative finite between labels - because there are only so many governments - but have a fully dynamic supply within the label. That focusses the currency on transactions, not hoards.