It's easy to explain: it's raw, unadulterated primate tribalism.

Multiple studies have shown how tribal psychology overrides pesky things like logic or coherent, and it's terrifying how much people will excuse or rationalize in order to remain in good standing with their tribe.

Demagogues know this very well, as one of the first things they do is force their followers to hold contradictory principles as a kind of shibboleth. It softens their followers up for what's to come.