Here's your choices:
1) Killed by cleaners doing the bidding of the elite to protect them and cover up their misdeeds. If so, the reach of the mighty is total and that would explain why so many politicians and public figures are scared to commit to changing anything and why police detectives commit suicide mysteriously and why so many public officials "fall in line" isn't just to keep the dental plan but to stay alive.
2) Committed suicide because he was either loyal to a foreign intelligence agency or to whoever is on the other side of the people he was helping blackmail. A disciplined foreign agent? Seems unlikely. Maybe more of a rogue agent or someone who "left the reservation" as they say. Usually those types get cleaned up before they can do much damage, but suppose he was protected?
3) It is entirely possible that he entered a witness protection program of some high-level variety. I think this is less likely since those types of things usually happen after the trial and this was his own trial but the evidence entered into the record would likely have implicated many public figures and well known people. I would venture as far as saying 99% of those people would be Democrats. Sorry to make it partisan, fwiw GOP establishment people are just as crooked, but they accept bribes.
3a) Like the allegations surrounding Ken Lay, maybe he had enough money to create his own escape? It would be "allowed" the way it was "allowed" that El Chapo escaped from prison in Mexico. Bribery, deals, etc.
4) Facing the prospect of remaining behind bars for the rest of his life (10-15 more years?) he took the coward's way out as did so many evildoers before him. Recall that he hobnobbed with the fanciest and most fast moving people in the world and to be brought low like this is impossibly damaging to that kind of personality. It's also possible, however unlikely, that his conscience finally caught up to him. He certainly did abuse a lot of young women.
What have I missed?
I'm enthralled but also disgusted with what is going on these days. In the span of just one week we've seen 8chan taken down, which, even if you hated that place, you have to admit was a major blow to actual freedom of speech on the Internet. Someone used influence and corporate preference to do what governments couldn't do, which is shut up a vocal minority asking real questions. We can't even have the barest, most meager free speech, not really. Yes, that site was full of antisemitism salted with kiddie porn, but I suspect that stuff was spammed there by agents provocateur in order to chase away the curious. It was just too constant a thing, as was all the astrological horseshit and other attendant, easily debunked nonsense. How better to marginalize dangerous minds than to apply the "child porn" label to them? There is no better way! Wait until "Red Flag" laws get weaponized.
So Epstein is dead or won't be heard from again, at least. Assange is next. What after?
The entire Western world seems to be sleep-walking right into totalitarianism. When we lose the rule of law or when there is two sets of policies for the elite and for the "rest of us" or for the "party loyal" that portends the next wave which is violence. It is entirely clear that violence is what is sought, too. They aren't even pretending to care what moderate people think anymore or who ends up being harmed, as long as power keeps concentrating.