It is 100% truth that cryptocurrency can not replace fiat, reason being that fiat is a legal tender of each country and can be use to purchase any goods in d market but crypto currency can not be use to purchase goods in all market except selected market and those market can only be a market that specifically accept crypto currency.
You are right but one thing that you said which caught my attention is that fiat is a legal tender. What is the meaning of "legal" as used here?
I think if crypto is accepted by governments, then it will be called legal as you used. They are making it look illegal but it is a human who makes things legal or illegal.