You're mixing up things. I can draw a one-off picture, that doesn't make the drawing valuable (sadly. If you want to buy my paintings, hmu). The value needs to be attributed by a shared denominator, which for the example of Mona Lisa is cultural prestige. Crypto has zero inherent cultural prestige, it's only value lies in social attribution. Wallets on hard drives are meaningless unless we decide that they aren't. The mona lisa isn't worth what it is if we decide otherwise, but it does have inherent value. Crypto does not. For crypto to have value, someone else needs to pay Dollar/Euro/whatever at an exchange. That's the value of crypto - the exchange rate.