He's about as much of an idiot as we've seen in recent times. When MJ (and Farrah and McMahon) stories hit, you would have thought that he would have tried to just slink away, hoping that when MJ's story died out, Sanford would be a bit stale for coverage. Instead the idiot kept going on TV...
The 150 year sentence is symbolic - 50 years would have sufficed if the other crooks in his family could also get roped in.
As you noted, his family did their level best to syphon money to their accounts. Even whenhe was under house arrest, he tried to ship out the valuables. For starters...