Scamming is fun, you don't have to be predictable or reliable or follow social norms, and your ceiling is limited by your own desire rather than a time schedule or a pay structure. (Of course, these days some scammers run firms with office space, schedules, and incentive structures!)

Also, a score yields some satisfying resentment; you're getting one over on those bastards.

I think a lot of people don't really have a good theory of mind of career criminals. The vast majority aren't regretfully finding themselves driven into crime; they like it and it's fun.