I don't care about the taxes so much. It's the linkage to my online personas that I care about. And I just don't want to deal with questions that might touch on them. Because I know a little about interrogation, and I know the risks of lying to investigators.
And the freakiest thing is that I have no idea what sorts of investigations some of my personas might be part of. I'm a decent guy, myself. And much of my Bitcoin came from writing, mostly for IVPN.
But I've also done some consulting with other anonymous cowards. I'm adamant about not wanting to know anything about what clients are doing. But I gotta wonder, sometimes.
So anyway, keeping online and meatspace finances totally separate is just part of my OPSEC.