In one of the topics I read "If bitcoin will reach $10.000, fiat currency has become worthless"
Do you agree with this statement?
Not at all. Even if BTC will be $100.000 fiat will have value.
The reason why fiat, btc, eth, xmr, etc has any value is because us (users) are trusting it and using it.
Why is valuable a $20 bill?
Theres nothing inherently valuable about a $20 bill. The bill has a value because weve all decided it should.
Money is about the exchanges and the transactions that we have with each other. Money its about a collective story that we tell each other about value.