In the real world, a prosecutor can only nail a higher-up with the cooperation of the people lower down. Those people only cooperate if they get a lighter sentence. It's too bad, but that's how it is and it plays out every day in criminal courts.
As for Diddy: a real, disinterested DOJ would say, "oh, you can testify against <people more famous than you>? Well, we might be able to cut you a deal."
Of course, if the DOJ is not interested in prosecuting those people, then no deal. If they think Diddy is already important enough and they can't let him slide, then no deal, or at least, a medium-stiff sentence.
Finally, two years in prison is not a picnic. See if you want to do it.
As for Diddy: a real, disinterested DOJ would say, "oh, you can testify against <people more famous than you>? Well, we might be able to cut you a deal."
Of course, if the DOJ is not interested in prosecuting those people, then no deal. If they think Diddy is already important enough and they can't let him slide, then no deal, or at least, a medium-stiff sentence.
Finally, two years in prison is not a picnic. See if you want to do it.