The true losers of 2016, besides America, are the pollsters. What the fuck happened? Did everyone decide at the beginning of 2016 to just lie when people ask them how they're going to vote. Jaysus.
The pollsters rely on a number of factors (which I don't understand well enough, so I'll leave them vague) which are simply outdated. For example, they do not take into account the ever-growing number of people who have all but opted out from traditional media, and who instead rely on social-media-based alternatives. A decade ago, the amount of negative publicity Trump received from the media would be the kiss of death for his campaign long before the primaries. But that's just not the case anymore.
This is more or less what happened with Brexit, too. While exceptions apply, the division was mostly between experts and those who have (quite famously by now)
had enough of experts. When society as a whole begins to fail certain groups, these groups seek alternatives. Whether you consider them reasonable or not, people like militant MRAs/MGTOWs, the alt-right, or campus SJWs feel that the current order of matters doesn't work for them. They seek alternatives, and when they're sufficiently pissed off, they'll take any alternative that seems like a stern departure from "the system". Such behaviour is difficult to predict unless you're already on the inside of these discontent group.