How does one manage to be so fucking stupid?

Donald Trump literally thinks that you can just buy Greenland. Who does he think he is? Not to mention the utter lack of knowledge about international relations, the legality of it all, geology, biology, and not to mention the total lack of knowledge of people who live there. How does he manage to be the president of the US?<br><br>Edit: I am not sure if this is the right subreddit. But this sub was in the list of subreddits.