I maintain that this is the result of literally three to four decades of conditioning by voices they trust. It began with Limbaugh and talk radio, added to it with Fox News, and then finished with the internet.
Every voice they trust is completely one-sided, and steals from them one of a person's most imporant qualities: Curiosity. An intense ideology like this robs a person of their fundamental human curiosity because it provides all the answers. That's what creates the short-sightedness and unyielding nature you describe.
It's especially frustrating for people like me, because I have several general agreements with them on issues. But this binary, caveman approach they apply to any given problem and situation simply cannot work in the long term. Unfortunately, their thought process are too calcified for them to see it.
Someone once said that the difference between liberals and conservatives is that liberals are never sure they're right so they question everything, and conservatives are so positive that they're right, they never question anything. Simplistic but close enough.
But yes, right wing talk radio, echoed by their clergy, and their media, poisoned their minds. And then convinced them that MSM was SO left wing biased, and untruthful, they were not to be believe, even though studies showed a slight bias of less than 10%, and high marks for factual reporting, and verification of sources.
Right wing media is virtually all privately owned by billionaires, who exercise absolute control over what's broadcast/published. The Mercers (Breibart) actively worked with the Putin and the Russians through Cambridge Analytica, on ensuring a win for the Brexit side in the first Brexit vote.
And just as they try to silence and ostracize all critics within the Republican Party, they cover their eyes and ears and call us "liars" and "haters" because we refuse to buy into the progaganda.
I read an interview with the owner of a right wing "fake news" internet site. He was asked why there are no left wing fake news sites and he said they had tried to run left wing sites but every time they posted a story, it was debunked within 10 minutes of it going up on the sites. Leftists fact checked everything!!!!!
If the story supports the most closely held beliefs of conservatives, and, as you said, it comes from a trusted source, they'll never question it or fact check it. Tucker Carlson is that "trusted source" today even though he has been publically outed as having lied to the American people, over and over again.
Even more distressing in this scenario is that Carlson is cosying up to Putin and Orban, and did that interview with Putin. I saw a couple of Midwestern Americans being interviewed about their views on the Ukraine and they asked about Putin, and they responded that they thought Putin was a bad guy too, until Tucker interviewed him, and if Tucker says things are great in Russia, they believe him.
That was like a bucket of cold water in the face. Yikes!!!