Greed is a complex and consuming emotion, don't underestimate it's ability to ensare people.
I hear people all the time saying "if I made a startup and sold if for millions of dollars, I'd retire and never work again", when most people who do make millions on their startup continue to work. It's that work ethic that is what made them that multi-million dollar startup.
Whether criminal or not, there's a particular work ethic that keeps people like this making more money when they could retire happily.
The dude who sold their startup doesn't have much to lose at that point to take another shot.
The criminal though who goes for that extra million can lose it all.
Very different risks and stuff to weigh.
Thank goodness criminals are dumb!
Are they all dumb, or is it that only dumb ones get caught and you end up reading about them, while the smart ones carry on undetected?