My opinion is “US and Canadian financial law” biased, yes, since that’s the rough domain of interest in this thread.
There’s nothing illegal about P2P crypto transfers, assuming that you’re not (1) circumventing currency transaction laws, and (2) paying the appropriate taxes. Since the people who might do P2P transfers in this scenario want to avoid the scrutiny of the law entirely, I think it’s safe to say that this does indeed fall under “doing two crimes at once.”
Not necessarily, p2p and cash.