Question here: What is the purpose of a sentence this long?
I understand that for this type of crime the goal is deterrence rather than rehabilitation, but let's say we had a habit of locking up corrupt billionaires for 20 years instead of 50. I'd argue that the lost opportunity cost for people that wealthy (or really for anyone) that 20 years is as much a deterrent as 50 years, but at a lower cost to the tax payer.