I wonder what the solution is?
The easy criticism is that these people are just "dumb," but it goes beyond that. Plenty of people who would score well on IQ tests behave irrationally just the same. Raw intelligence doesn't necessarily confer the ability to recognize your innate biases and weed out disinformation. An example is Nobel Prize winner Michael Levitt, whose opinions on the pandemic are about as dumb as a Trump 's opinion on politics.
I think the primary barriers to rational thought are pride, ego, and a stubbornness to concede beliefs because you don't want to give the "other side" a victory. And this at ude is symptomatic of a deeper American sickness that prioritizes "winning" above all else. It's precisely why Trump got elected.
My solution is that we need to expand the concept of "education" beyond just having students learning by rote from textbooks. We should emphasize to children in their formative years the ideas of humility, introspection, and not to fear failure, that "losing" is okay if you learn something. That cliche of "It's not whether you win or lose, but how you play the game" needs to comeback en vogue.