You have hit on a characteristic that is common with narcissists and it is related to my comment regarding an authentic self; they have no originality.  They mimic, mirror, and emulate others, adopting beliefs, activities and values of those they target, and they are dumbfoundingly skilled at it.  Their acting abilities are beyond what most people can understand, possibly because in the moment they believe themselves. One victim stated that they fake emotions better than ordinary people feel the real thing. It is regularly seen in abused spouses who have difficulty leaving their abuser.   The abuser turns on the charm, promises, goes on best behavior, woos, "love bombs," and ordinary people cannot believe that anyone who didn't really feel that way could possibly exert so much effort to lie.

Trump's voters are going to have difficulty believing they have been conned as much as they have, but they will.  Disillusionment is the only possible outcome to this disaster.