Crypto will never crash the system and replace money, at least not in north america.Everything is enforced by laws, like a law that tax needs to be paid in cash, on all items, no matter what the person pays with.Sometimes it feels like people think if we all go crypto, money is somehow going to be free, and life is going to be so much easier, I don't think that's true. Imagine if you could only buy bread with crypto, and some billionaire buys a large amount of crypto the night before, the next morning your bread will cost twice as much. In other words its a rare resource, basing prices on crypto doesn't make sense.It can represent money all day long, and have value based on the dollar, but I don't think it can be money, unless governments just make digital cash for us, that doesn't jump too much.
Imagine you buy 10 loaves of bread with fiat currency for $5 total, save the money in your savings account and the next day a billionaire buys up and hoard most of the basic things in the market and those basics things double in price due to scarcity... [Printing too much money than is needed can also cause such inflation.] And the little savings of the poor saver is devalued.
Or
Imagine selling your cherish bike for $3,000, you keep the money in your savings account long-term, and next 7months the currency loses value due to inflation of basic goods and services.
I think deflationary currency will be best for both the bread and bike savers. A moderate deflationary currency can function as both "stablecoin" and normal cryptocurrency