Most of these people generally have a high intellect and are fast learners, not just in their profession, yet they don't seem to be able to see why other people might have different believes.
An example can be found in this video:
https://www.youtube.com/watch?v=HURvJDldVGA
In it, the author talks about why a programmer might hate Scrum. Going into it, I thought they might point out things I, or the dev team can improve to make Scrum fun again. Yet, the only people that are blamed are project managers, and never the programmers, which seems to be the profession of the author. While I somewhat agree with their points, I highly doubt that it's never the fault of a programmer, which is implied in this video.
Another example for this is farming and politics. I grew up in a family of farmers. Ranting about how politicians are destroying our industry was 90% we ever talked about. If I talk to some other people, it's the farmers who are destroying our planet.
Do people actively ignore other opinions to leverage a better outcome for themselves, or are our brains just not able to find a common ground?
It’s not just a trait of exceptionally evil people but rather ‘self-love’, which is a part of your mind just as your heart is part of your body and it goes wrong in so many ways just as you can have a heart attack, heart disease, heart failure, high blood pressure and many other conditions.
Specifically when many people feel bad about themselves it causes in instability in their psyche, in an extreme case it is like dr. Heckle and mr. Hyde. But it explains why politicians pander to people so much.