>Ukraine received a bunch of international crypto donations last year, for example.
While cryptocurrency was used to donate to Ukraine, a bank transfer or Western Union would have done the trick too -- since no one (except maybe the Russians) would consider such donations criminally actionable.
Which was my point. Sure, foreign remittances, sending money to friends/family and other mechanisms allowing money to be transmitted around the world is certainly a use case for cryptocurrency.
The rub is that for the vast majority of legal transactions (i.e., those that won't raise government hackles), cryptocurrency is currently riskier and less reliable than using a government-backed currency.
That's not a dig at cryptocurrencies. Rather, it's an assessment of the current financial ecosystem. Cryptocurrencies have lots of potential but, like most immature technologies, it's not quite ready for prime time.
As such, the vast majority of folks who choose to use cryptocurrencies as a medium of exchange are those who either don't want their transactions detected by the government (the vast majority of which are those things that raise government hackles) and/or those who are risk tolerant.
Which is why cryptocurrencies are mostly used as a medium of exchange on the fringes of society/legality.
As the technology matures, you'll see cryptocurrencies become more and more mainstream -- even government-backed currencies. Because, in the end, cryptocurrencies are just another form of money.
For now, the primary use case for cryptocurrencies as a medium of exchange is avoidance of government knowledge/involvement. Eventually that will change, but I'll probably be dead[0] before that happens.
[0] If I'm still alive in 2050, I'll be surprised.
Edit: Clarified my estimate for when cryptocurrencies will be pretty mainstream.