I agree with you in general. There have been successful prosecutions which have resulted in significant jail time. Although the Supremes have yet to weigh in on the latest batch[1], and right now it's not looking good for the Feds.

But I disagree with you about Stevie Cohen. Quite a few of his underlings took a fall, but he personally emerged scot free. He simply wrote a very big check and made his problems go away. He's busy managing his remaining billions in a "family office".

[1] http://www.nytimes.com/2015/07/31/business/dealbook/us-asks-...