Well there's the disconnect.
Musk is, and please excuse my language, a ******* idiot. He THINKS he's a smart person... because he has almost all the money and makes actual intelligent people (like various flavours of engineer, software developers, and business managers.) agree with him. He's another person who exploited others at every step, was very good at selling himself, and failed upward.
Does he believe trump will be good for the US and the world? Probably not, but a trump administration will be GREAT for musk's bottom line, and that's the only thing he actually cares about. He's a high functioning sociopath who started his career in this world by stealing emeralds from Afrikaners.
Musk is a smart person in the same way trump is a rich person. They are caricatures of stereotypes.