I think I know why tRump decided to run for president: He heard the phrase "the buck stops here".
Seriously though, he's always been a greedy self-centered asshole. Why anyone thought he'd suddenly rise to the office once attained is beyond me. His primary concern always has and always will be himself. We've all seen the recent photo where he hogs the umbrella, forcing his wife and child to fend for themselves:

If he's not going to put his family before himself, why would anyone think he'd put the country before himself? That leads into this not-so-shocking-but-still-shocking revelation that
he thinks a terrorist attack might be good for him politically:
“In private conversations,†said the Post, “Trump has told advisers that he doesn’t think the 2018 election has to be as bad as others are predicting. He has referenced the 2002 midterms, when George W. Bush and Republicans fared better after the Sept. 11 terrorist attacks, these people said.â€
Could this be a precursor to a LIHOP event? (I don't think he's capable of a MIHOP event). That he would even consider a terrorist attack as a positive shows how depraved his mind is.
This follows a story from last year that is completely relevant with a government shutdown looming tomorrow night, where tRump mused that
a government shutdown might be good for him. Forget how bad it would be for military families, civil servants who go to work each day trying to do their part to make the country a better place for all of us, park rangers, etc. Screw everyone else if it helps him in some small way. Does he think this will bring the Mueller investigation to a stop?
A president's number one concern and responsibility should be "we, the people". For tRump, it's "me, the person".