IMO the government is designed to make sure that unreasonable people don't hold power. The fact that it takes a while is part of the reason that reasonable people can and usually do. We are a nation of laws, not rulers. Trump is currently a US president. If he wants to be a ruler, it is going to be an arduous process on his part. I am not saying that it isn't possible, but the question is whether he can defeat the legal system before it defeats him. The fact that it is difficult to remove a bad president is what creates stability for the good ones.
He's also playing a game as a Level 1 newb while surrounded by career Level 80 arch-mages. They've opted not to frag him so far but they can change their mind whenever they want. Oh, look at that. The Attorney General has ordered the Justice Department not to defend Trump's muslim ban in court.