Hi, I think about this sort of thing often and have come to the personal conclusion that humans' chief vice is stubbornness. Please allow me to explain because the stubbornness is more of an effect than a cause.
Humans couple identity & belief very tightly. For example, people say things like "I am Republican", which doesn't imply that there is a subspecies of humans called Republican as an alien might think, but rather that they generally believe in the republican party's views. This is the start of it.
Somewhere along the line of growing up, identity becomes a very big deal and puberty hits you with "Shutup mom & dad, I believe in [this] stuff cause that's who I am!" This is actually rather healthy as the teenager is becoming autonomous and self-reliant, but is accompanied by the damaging effect of My Beliefs = Who I am. For a teenager that does not know not to believe in self-debilitating thoughts, they can quickly wind up on the road down to depression.
Furthermore in this world, specialness is generally coveted. A lot of the nerds around here might know Enders Game in which a kid kills a civilization that is arguably more peaceful than our own -- the society worked like a bee hive and did not understand personal dogmas or behavior that centered around the individual. While it's scary to imagine a queen bee ruling over all of us, there's still something to be said about if we focused on working together.
However, that's not this world so what you end up with is people equating their specialness (and therefore value, and therefore self-value, and therefore self-esteem) with their identity, which is defined by their beliefs & physical appearance. If they only could stop caring so much about special, it wouldn't matter if you were right or wrong because you would be on a natural hunt for goodness and knowledge in all its forms. Yet, from the competition to be special comes this behavior.
It's not that people want to be stubborn, but in linking their identity with their belief & thought, they now feel literally attacked if they are wrong. Nerds, who many already suffer with self-esteem issues, thus feel good to be a mental champion because it reinvigorates their self-esteem.
For some of us, we hold our identity in spirit and therefore feel detached from the human existence and do not let it bind us in this manner. I'm not perfect and saying everyone should follow me, but generally speaking, I do believe if people truly evaluated where they get their feelings of self-esteem from, they might be a little startled to see how much of it revolves around petty things like the need to be right.