>>Isn't that a sure way of not getting anybody competent ? Isn't that the hallmark of incompetence to think that you are better than everybody else.

Not necessarily.

There are two extremes. The first one is the Dunning-Krugger effect, where the person is so incompetent that they are not able to even recognize their incompetence, and instead think they are awesome. The second one is the opposite, called the Imposter Syndrome, where the person is extremely competent but believes that they are actually a sham who just got lucky.

There are many extremely competent people who are aware of their own competence, though.