Putting people in jail is a deterrent. You do that and rich people start thinking very hard about breaking the law like that because suddenly it’s very much not worth it. They are already rich, losing a few mil is annoying but going to jail is devastating, especially when it’s so easily avoidable.

And now the rich are paying more taxes and so you make more money. Catching and convicting people of fraud isn’t exactly cheap either, and don’t forget that not everyone will be convicted.