A good answer to the most puzzling question.

Why do Trump's supporters stand by him, no matter what? So asked Bob Altemeyer about two years ago. Given all the swill that's spilled over the dam since then, the question seems even harder to answer, but he had it nailed way back then. Do read the whole thing. The gist is that people with authoritarian personalities don't think for themselves at all. You can't reason with them because they were never reasoning in the first place. They just want to be told what to think. Pull quote:

[T]he fidelity of Trump’s base remains astounding. He has made so many unforced errors because of his lack of understanding and low problem-solving intelligence, his vast ignorance, his enormous, never-ending dishonesty which seems as reflexive as his breathing, his explosive hostility, his uncontrollable vanity, his despicable demeaning of women, his squalid vulgarity, the stupidity of his stereotypes, the shabbiness of his thinking, the buffoonery of his parading, his attacks on the institutions he needs most to safeguard the country, his incredibly poor judgment about the character of those whom he has brought into his administration, his equally mind-numbing lack of judgment about foreign leaders, friend and foe, and  his willingness to inflame Americans’ disagreements and turn them into conflagrations which make us that deeply divided house which the Gospels and Abraham Lincoln warned against—how can his supporters have stood so solidly behind him? You’d think they’d be having some second thoughts at least. . . .

Compared to most people, studies have shown that authoritarian followers get their beliefs and opinions from the authorities in their lives, and hardly at all by making up their own minds. They memorize rather than reason. . . .When your beliefs are memorized copies of other people’s opinions, you don’t really know why they are right. That means you don’t know IF your professed truths really are true. So how do you maintain your beliefs should events and discoveries contradict them?

Researchers discovered decades ago that people validate their social opinions socially to a certain extent by selecting news outlets, friends, and so on that will tell them they are right. This produces an illusion of consensus, at least among all the “right” people like themselves. Almost everybody does this, but authoritarian followers do it much more because they don’t have many ideas of their own, beliefs they have worked out for themselves and can defend. And they are much more likely to expose themselves only to sources of information that tell them what they want to believe. Getting only one side of a story raises the chances you will get it wrong, but as Ralph Peters, formerly the military analyst at Fox News, said recently, “People that only listen to Fox have an utterly skewed view of reality.”

So there is no sense trying to reason with these people. They are blind sheep.