There’s nothing illegal about cryptocurrencies. It’s just random numbers and code.

However, those random numbers have actual value, and governments regulate some transactions, particularly ones that cross national borders, to make sure those transactions do not hide a crime or go to individuals who the government has put under sanctions.

Some people of a Libertarian bent get involved in Crypto to keep their governments out of their business. But those laws still apply, no matter what the medium of exchange is, or how much those people whine about those laws.