Damn taxes.
This is BS. I've seen a lot of rich people who commit huge tax/financial fraud getting a slap on the wrist. The only one I can think of who served time is Martha Stewart and she got 5 months in a min-security prison. Actually min-security is a misnomer. I think it was an open prison that she could leave during the day and return at night.
I guess because these guys come from a "quesionable" industry, they get hammered.