He was talking about making good money in IT, so I asked why he didn't continue working in IT. (At least that's how I remember a conversation from over 20 years ago.)
He was originally talking about playing computer games on early computers, so I thought I'd get a story about why he left tech. (IE, laid off and had to change careers, couldn't keep up with changes, didn't like the stress.) I was quite surprised that he was a felon.
He really didn't tell me much about what he did, either. I don't want to repeat much here, other than to say he got greedy.
At a high level I don't think there's anything wrong with what he did. There's plenty of legal activities that are "grey" morally: Oil companies, tobacco companies, investments (stock, 401ks,) where ordinary people don't realize the nasty things the companies they own do...