Another common "career progression" is for attorneys to become judges. Now we've established that everyone in the courtroom is "seedy". Still, citizens are often surprised by the awful performance of the USA justice system.
Anyway, the defense attorneys to whom poor people have access (public defenders and other low-cost providers) are seldom former prosecutors, so they could possibly be decent humans. That they face so many obstacles is a good sign of the priorities of the system.
If you think prosecutors are seedy you should feel the same about defense attorneys.