Trump has the concentration span of a gnat. The ghost writer of "Art of the Deal" confirms that fact and calls him a sociopath. He would never be able to sit through the presidential daily briefings. He'd go crazy! He's admitted that he gets his foreign policy knowledge from "The Shows"!
Going to a summit where he'd have to listen to endless boring speeches through interpreters would make his head explode. They'd have to take away his phone so he didn't tweet and mock the emperor of Japan as he was speaking.
He doesn't want the damn job and apparently some people don't quite understand that simple fact.
Trump will resign within the first month or two of being elected.