Actually, I believe these people (the elites) are so detached from the reality of average Americans that they cannot grasp or fathom why we support him. They live in a completely different world.
The #NeverTrumpers are not motivated by principle but by fear of loss of power and influence.
In a word, they backed the wrong horse and now the chickens are coming to roost for them.
Too bad, too sad. They made their bed and now have to lie down in it.
That's likely true, but they also are acting this way because he's a huge threat to their egos and their stature. This is also why many on the left also hate him.
He has exposed the fact that politics is peppered with people who are impressed with themselves but who are not that impressive. He exposes this, and ridicules them. I don't like or believe in ridicule in principle, but they've earned this ridicule because of their arrogance and their willingness to ignore the effects of what they do on the people they are supposed to be serving. Many if not most of them truly think they are ‘special’, and better than the rest of us. Trump essentially tells them they're incompetent, and even calls them clowns.
This move to try to run a third party candidate flies in the face of the voters, and they're doing this because they are childishly angry that they aren't getting their way. It's really no different from Obama using executive orders to ‘get his way’, or Jonathan Gruber alluding to fooling the people about the health care bill, or Pelosi admonishing that ‘we have to pass it so that we can see what's in it’ in her attempt to push through a bill that has raised expenses for health insurance dramatically for a great many Americans and threatens to end much of what has bee good about health care in America. This is the arrogance of those who in their delusional grandiosity think that you have to actually be talented and smart to be in politics.