Because it's easy. You don't have to think - deal with the topic.

It's a nice feeling to always be right. So you can divide everything into yes or no. You agree with what you see as correct, because you know that this is correct. And what is not right is rejected. I call these people white-black types. The less you know and think, the more you approach it.

How can we prevent this?

Well, by orienting yourself in many ways. And avoids taking extreme positions, stays mentally active and above all by recognizing that there is a wide range of different possibilities between black and white, which can give people more clarity and enrich them.

Another comment: Man has the world in his head (in the brain) that he once experienced. Now the world keeps turning, changing.

If he doesn't get any new information, he stays in his old world, so to speak, which is different from the changed one.

And: There are quite a few people who think they are much smarter than everyone else. Often because it creates a pleasant feeling.

This arrogance is often paid for with errors of judgment.

This can be seen very well, for example, in the feeling (belief) of free will or that the person makes conscious decisions (and not the brain).
 
Without a doubt, feelings have a central, healthy function for humans.
 
But: without question, they don't always make the right decision.
 
Restricted emotional life (often genetically determined) can bring considerable disadvantages for humans, similar to the consequences of frontal lobe damage.