Pride often gets in the way of common sense. I learned this early in New York. One night, a group of us left the dojo to spend an evening at a Japanese restaurant with our Sensei’s (teachers of martial arts). It was a memorable evening because Sensei’s teacher was visiting us from Japan, and we wanted everything perfect.
Finally, after a beautiful evening, our group broke up, and my Sensei’s and I walked towards the subway.
About halfway there, a group of hoods assaulted us. After attempting to defuse the situation, Sensei’s teacher took the assault head-on. Moving gracefully out of the way of one assailant, O sensei ( senior or older Sensei), tripped another and gently grabbed the third by the wrist, and bent him to the ground. The fight was over in seconds.
The idiots got up, backed away, and began screaming at the elderly short gentleman who had gently put them out of action. Then, not thinking that it wasn’t luck that they had been defeated, they moved in for a second try with similar results. Finally, O sensei grabbed and immobilized one of them to show us how the particular wrist lock he was using worked. He then casually tossed the oaf away. They ditched their idiocy and made a run for it.

My Sensei reviewed the street incident in great detail at our next meeting. He pointed out that O sensei had attempted first to avoid fighting and only defended himself when necessary. O Sensei used only as much force as needed to restrain his opponents. His opponents did not see that their tactics had not only failed but were sure to fail again.
His final point was that O sensei was only five feet tall, very slight, and seventy-eight years old. So, naturally, they assumed that such a frail older man would be no match for three burly men.
He concluded that their pride had defeated them by blinding them not once but twice.

We all allow pride to blind us. We spend years at college learning a profession and think our learning makes us infallible. We consider warnings that there might be unknown factors as spurious. Or dismiss as vulgar rants the opinions of those that disagree with us. We insist that we can do it, and don’t carefully evaluate the actual situation

Worse, we repeat our efforts even when they fail multiple times. I’ve become convinced that we do this because of a sense of investment. We spend so much time working on something, learning something, and owning something that abandoning it is almost impossible. So when we get confronted with the little elderly gentleman, we are confident that there is no threat.
We are rugged, confident, and muscular. He is little, old, and weak. The conclusion is we will win.
Not knowing that he is a ninth-degree black belt could be the weak point in our tactics.

If you have an opportunity Google Murphy’s Laws of Combat, there will be a heading in most versions that states that the guys in the simplest uniforms usually win. They have no medals or fancy uniforms and look very unimpressive. I think this particular heading was added after Vietnam, but it points out that what you don’t know can hurt you and, as the old saying says – Pride goes before the fall.