Well...he didn't initially understand the ramifications of nuclear fallout without needing to be told in no uncertain terms, he's given away key information to foreign diplomats in order to [i]brag[/i] which has put lives in danger (the agent in question possibly died), he didn't know the uses of uranium, he didn't know that he wasn't the largest republican lead in a race since Reagan, he thinks coal power is clean, he's bankrupted a casino, he needs 1 page paper reports with his name mentioned often in order for him to continue to pay attention, and these are all without me needing to look up things I might have forgotten. 

I don't hate him. I think he's bad for the presidency, definitely. But take away the name Trump, the GOP, the presidency, all of it, and look at all of the above about some random dude. You'd call him an idiot.