Like Monero, fiat currency has no intrinsic value but derives its value from popular decree and public trust in its stability. The difference is that fiat is legal tender, and people are obligated to accept it under civil and criminal legislation. No one is obliged to accept Monero in payment, or for the settlement of debts public or private.

To date, Cryptocurrency has only ever constituted legal tender in two countries - El Salvador and the Central African Republic - and El Salvador revoked their BTC legal tender law.

>value from popular decree and public trust

There is very much a third way it can gain value and that is features. I and many other value mass acceptance below anonymity, privacy and decentralization. There is a small but steadily growing community of people accepting monero https://monerica.com

There is always the way to swap them for other coins like bitcoin with all there drawbacks.