Well, let's see - the list is lengthy, but the top few matter.
He pissed off Daley by trying to display some independence.
He pissed off Mike Madigan, Speaker of the IL house by trying to rein him in; Madigan's daughter is IL Atty General
bho owed him nothing
That ought to about cover it. He got thrown to the wolves, and found he had no friends when the Feds came acallin'.
Agree on the sentence though, but typical of a lot of sentencing disparities, like the murderer who gets five years, and his roomie is in stir for 20 years for possession of a pound of weed.