The Dunning-Kreuger effect seems to have played out overnight here in Australia. Just had a phone call to say yesterday's federal election has put back the same Coalition party. I feel sick and saddened that we appear to have learned nothing from the last four years.

This meme reminded me of what you said

A major cause of the Dunning-Kreuger effect is instilling in to very young children the idea that they are in some way or another superior. By giving them a false sense of confidence self righteousness and infallibility you create a self justifying idiot who can never know he is an idiot because that in itself is, to him, a stupid idea.
Either by religion, ethnicity, religion the child is made to think they are privileged and must never let anyone tell them they are wrong, especially if that person is "other".

For example my father would never accept that he was wrong about anything if my mother corrected him, it was simply impossible that a woman, by virtue of being a woman, could possibly know better than him. Even if I or my brother backed up my mother as being correct, then he would say that proved his point as the woman was only parroting other men and did not understand what she was saying herself.

In the USA children are raised to believe themselves privileged to be citizens of the greatest country on earth, to be "white" American is both to be a member of the greatest nationality AND the superior race. TO be White American and MALE is to be unassailable regardless of any other factor such as education.

When Trump came along and showed himself as a White American Male who agreed with these self deluded idiots and justified their belief in their own false self confidence it simply reinforced what they "know" to be true and provided a totem to rally to.

It is also a function of manufactured consent, described so well by Chomsky. Not all of the trumpies are stupid. Many are, but not all. No more so than the Nazis. Scary, you know?