Cognitive dissonance and cognitive bias are fundamental to psychology. We avoid paying attention to things that disagree with our model of reality and grab on to things that confirm our preconceptions. It is very expensive in time and attention to build a model of reality that doesn't conflict too much with personal experience, and we don't take kindly to things that wrinkle that tablecloth, as it were. It takes training to overcome this, and then only imperfectly.

That's part of what makes propaganda delivered by the MSM so effective. And it's what makes getting along with relatives over the holidays so crazymaking.