Donald Trump is not stupid, and that is scary. His opponents are quick to call him ignorant of the laws and stupid for his tweets and getting mad about silly things, but the truth is he knows what he is doing. Unfortunately, that makes Trump much more dangerous.
First of all, Trump is great at taking advantage of his supporters. It is common knowledge that people tend to believe those who agree with them, and Trump knows that. For example, he said that his inauguration crowd was the biggest ever. That is simply not true. However, his supporters will believe it to be true as long as the people they trust are saying it is. By denying facts, Trump is changing what the truth is to his supporters. It is like in George Orwell's classic 1984. If the government insists that 2+2=5, and they force people to believe that, 2+2=5 becomes fact in that society. Trump knows he can make up any fact he wants and people will believe him, and he is using that to turn the American people against his enemies.
Donald Trump is also great at switching his positions based on who he is speaking to. While people may hear in the news that the candidate they support switched his position when speaking to a different crowd, that person is likely to think that this new position must have been taken out of context. Trump can switch his positions as much as he wants because he knows his supporters will only listen to his statements that they agree with and block out the statement they do not.
Possibly the scariest thing Trump has done is block the media from several different speaking engagements and even the White House. Most presidents would be widely ridiculed for doing anything close to that. However, Trump can get away with it because he first portrayed the media as bad. By continually bashing the media and calling it "fake news," he was able to turn people against the media. After that, banning the media from the White House comes across as him doing a good thing. In reality, Trump is saying things behind closed doors that he does not want anyone to hear, and that is scary.
And finally, Trump is great at turning attention away from his flaws when he needs to. If he is under fire for something he said, he can just say "Hillary's Emails!" and his supporters are back on his side. If he wants to do something like bomb the Middle East, he can tweet something controversial to get people riled up about that and distract them from what he is actually doing. The stupid things he says are often used as a cover up. He is perfectly aware what he is saying is controversial, and he is feeding off that.
Donald Trump is not stupid. He is incredibly smart. That's why he won. And that is horrifying. It is time people finally recognize that Trump knows what he is doing, but not in a good way. We continue to fall into his traps, and that needs to stop.