Lol wat??
You don't have to believe in fiat, it exists and it works for day to day transactions. Don't know about its future.
The history of fiat money, to put it kindly, has been one of failure. In fact, EVERY fiat currency since the Romans first began the practice in the first century has ended in devaluation and eventual collapse, of not only the currency, but of the economy that housed the fiat currency as well.
I think not only of the Roman period but Fiat has been there since time immemorial. time of the prophet might still exist? fiat is already known from that tim. each country has its own currency perhaps it could be called fiat. I believe in fiat in the present or the future. fiat will always be exist