I think this is only part of the equation. IMO Trump is doing well largely for the same reason Sanders is: both come across as far more genuine than their competition.

Neither may be suited for President. But neither are following the same kiss-some-babies, state-inoffensive-truths, dither-on-the-hard-questions playbook that everybody else has used for decades. And that resonates with people, who are absolutely sick with politics as usual.

Both men are (again, IMO) performing a public service by throwing a wrench into the plans of the establishment parties. But I doubt either one will make it to the general election, because I think the establishment in one party would rather have the establishment in the other party win (and thus retain the status quo) than risk an outsider changing things.