Crypto was a huge mistake. It should have been rigorously regulated right out of the gate to the point of being unusable for anyone. I have yet to see a use case that doesn’t amount to buying drugs or defrauding rubes.
Sending money without government interference to relatives living in countries with strict foreign exchange controls (Argentina, Lebanon, Turkey...) is one quite legit use case.
While it is useful for this case, it is not 'legit', in that its purpose is to by-pass (break even) laws of the country with the capital controls. In that sense, money laundering is also a legit use-case.