That's true. Traditional currencies rely on the full faith and credit of some institution in order to convey value. I have yet to come across a cryptocurrency that has any meaningful story to tell me as to why it should have any value whatsoever.

Take Bitcoin as an example. People acquire BTC either when someone else transfers it to them (generally as a form of payment), or when their computer solves some useless math problem. I don't care about silly math problems, and the fact that you think it has value doesn't show me why I should think it has value.

I could see this "social proof" theory as a valid reason to believe BTC has value if enough people believed it, but that would essentially require that BTC be as ubiquitous as USD. If I can't pay my rent, buy gas, and hit up the local dispensary, and pay my taxes with BTC, the social proof theory doesn't apply strongly enough for me to even consider BTC a real currency. And, the story is even worse if you apply it to any of the more obscure cryptocurrencies (e.g. Monero, Dogecoin).