You don't use fiat as money. You use it as a currency. No one saves in it. In the us you save in harder assets like the 500 or real estate You're confusing it because were in this 50 ish year abberation where the functions of money are split

You've got a point, but would you agree there is a process by which the monetary tech with the best properties in a given context tends to win out over time. (I have personally come to think of "money" as the singular abstract information system that coordinates work and not any one tech, fwiw, and gold, USD, Bitcoin as "monetary tech." That's my mental model, anyway.) To your point, though, the proof of the pudding is in the taste and the context isn't simple. And sometimes particular incentive dilemma will keep us trapped in a bad local minima.