Of course you are right about Trump not leaving willingly if he loses. But it isn't the way that you are thinking. Here's the way it really is.
If Trump loses, Biden will mess the country up so badly, that EVERYBODY will welcome Trump back with tears and open arms in 2024. And Trump will be way readier than he is today.
EDIT: And if anybody says, look at how old Trump is already... There are tons of anti-aging technologies being perfected right now. Biden is too ... well, let me say that he isn't taking advantage of them. But Trump by 2024 will be ready.