that is by itself jail worthy
The closest comparable person I can think of was Madoff, and he had the leverage that at least most of his customer's money wasn't actually destroyed so his cooperation worth a lot. I honestly don't know that SBF has anything to bargain to the legal system or his angry, often crime involved, customers as it appears he destroyed basically all of their money. I'm not saying he should be terrified, but personally I would feel very terrified I were in that position.
I think his best outcome at this point is some form of plea that incudes witness protection program in exchange for un-"hacking" the remaining $600M.
Most mortals start sweating bullets if they steal a candybar, or at most a car.