Michael Jackson was chemically castrated by his dad so he retained his voice and as a side consequence he never fully developed mentally or biologically as a man.
This explains how he was able to sing even higher notes as he grew old against all logic. This is a good conspiracy because we all saw and hear the effects, but we cannot test, verify or confirm any of the reasons.

Now, the conspiracy that says Epstein didn't kill himself a separate category for I have a ton of questions, can be verified and the US government refuses to provide details of his associates and anything related to his death. Big bran time: everyone in the government is in the play.