The assumptions for my wild ass theory are that he thought the coup was going to succeed. Remember, he drove something like a thousand kilometers towards Moscow, AFTER it was clear what he was doing. There are videos of Rosgvardia soldiers just standing by and letting his column through. He was attacked by helicopters, and shot at least one down, so it was going pretty well. IMO he honestly should have just gone through with it, but that's only because I hold no value in his life or Putin's.

After it failed, I assume he knows Putin was going to at least try and kill him. That's why I think he would try to fake his own death.

But eh, that's just as likely to me as some other crazy 3D chess.