Trump and Sanders are manifestations of a long-term trend that has been building at least since the 2008 Financial Crisis. People are dissatisfied with the options they are presented politically, and economic participation is at historically low levels. We have never been more prosperous, but at the same time that prosperity and wealth gains are not only not very evenly distributed(they never really were), but large swaths of society are completely left out of them. In the early half of the century, it was a democratizing effect that everyone was drinking a 10c glass of Coke. This is just one example, you can also see it with iPhoneistas vs cheap Android phones, etc. etc. Now the hip drinks are craft beers and fine wines, and a former factory worker forced to work menial part time jobs is looked down upon for drinking what he can afford, Bud lite and coke. There are major class shiftings and reorganizations going on, and people living in and near large prosperous cities have largely been immune and isolated from it.
We dismiss and ignore their rise at our own peril.