With Cryptos you need to trust that you can convert it to fiat. Crypto trust is still a reliant on fiat trust. Any business accepting crypto, even drug dealers, need to convert their cryptos to fiat, because they need to pay the bills, pay their mortgage in system reliant on government enforced property rights.
The same was true for salt, and many more local kinds of money that existed.
It's also the same trust you need for fiat money. This, and trust that your government won't create a huge lot of it in an instant (slow rates of money creation are fine). Turns out that governments have a lot of leverage to enforce the first, more relevant kind of trust, so the total trust required decreases.
The idea of cryptocoins was to remove the trust on nobody creating a lot of money very fast. But in doing so, they also lost the leverage to enforce that people will accept it.