Donald Trump is an historical anomaly. There is no reasonable explanation for him. At least not at the moment. The context is too limited. Sure, we could probably explain how there is a Donald Trump. The why is more elusive.
A common definition for an internet troll is a person who sows discord by starting arguments or upsetting people, by making inflammatory remarks with the deliberate intent of provoking an emotional response or of otherwise disrupting normal on-topic discussion, often for their own amusement.
This seems to fit quite well. Trump’s political career reeks of trollish behavior. From birtherism, the Mexican wall and the Muslim ban to a media-politico conspiracy, Clinton coverup and “locker room” talk. There doesn’t seem like a day goes by without something outrageous that comes out of his mouth. His whole campaign is a troll on America and our political system (Trump’s brazen disregard for the 1st Amendment and the ridiculous #repealthe19th hashtag being propagated by some Trump supporters are prime examples).
Trolling is how Trump came into the mainstream. He’s actually been doing this for four decades. But it was the internet, Twitter specifically (see the exponential jump in Trump’s followers), that really enabled his startling rise in the political sphere. Trolling is the how. Perhaps a social scientist has more insight into why the archetypal Donald Trump exists.
The closest thing I could come up with is a quote from Christopher Nolan’s The Dark Knight, spoken by Michael Caine as Alfred: “Some men just want to watch the world burn.”
Fitting, as it is widely reported in the media that the Trump campaign is now engaging in a “scorched earth” strategy.