You meant prosecutorial discretion, right? Prosecutors do not have the power to put you behind bars, juries do.
I think you are barking at a wrong tree. Your beef is not that there are too many people in prisons, but that there too few. Specifically, white collar criminals walk free because they are either not prosecuted at all or if they are, they can weasel their way out by hiring high power trial lawyers.
For me, given the basic criminality and dysfunctionality of the US society, I am surprised that so few people are in jail. If I had my way, a big chunk of the corporate and political establishment would join ranks with thieves, dope pushers, and murderers that are already serving time.
Wojtek