belief perseverance and actions create your attitudes are the two main psychological components at play that explain why a trump voter may well double down rather than admit error (even to themselves. a fun fact is the person you most often lie to is yourself). People have to do this to protect their self esteem/image and avoid dissonance. If they're an admitted trump voter, they're also motivated to save face, and the world we live in today gives them plenty of leeway to cherry pick their information; dramatically compounding confirmation bias.
you have to know about these biases then you train your mind like a buddhist monk over years and years to think in opposite ways, and it's a lot easier to ingrain the younger you are when you start.