I think people around Trump nearest to him know he is mentally compromised in various ways

 So, the richest of the rich like Musk want to make money on the backs of the middle class and poor and that's all. So, they don't really care about the human rights of anyone anywhere. So, manipulating Trump through his ego and narcissism is a means to this ends of getting richer (which likely will harm everyone else) on earth including Americans.

I think understanding how an angry man with dementia that likely will take his life (because dementia is a fatal disease (within 5 to 7 years tops) is the way you have to look at Trump.

Whereas Biden may be diminished but he is still mentally fairly sharp. 

If you look at how Trump speaks and is confused easily this is one of the symptoms of his dementia. It is also one of the symptoms of his Narcissistic Personality Disorder too.

The man is 78 years old and already having such severe psychological problems I don't see how he could govern on any level with any good results in his present diminished state.

I think he is desperately running for president ONLY as a way of staying out of Jail.

And that might not work even then staying out of Jail either way especially because he is about to be sentenced by a state not the Federal Government at present. He cannot pardon himself for state crimes only Federal ones.