The US dollar holds value because the US demands you pay taxes in it. It also helps that you can actually use it to buy stuff - from an ice cream cone at a street vendor to an oil platform. And it is backed by a massive government, worldwide banking system, and not-too-shabby military.
Meanwhile, crypto is proving to be woefully ill-suited for any kind of payment, contract, or loan. The vast majority of its use is either speculation or crime.
Crypto seemed promising in 2012, but a decade down the line nothing convincing has come out. It is still a solution looking for a problem, and at this point I highly doubt one will come out of the woodwork any time soon.