because they're smarter than everyone else and
    there is nothing of value to be learned from others

Especially since everybody in the industry tends to be pretty smart.

When two people with intelligence within a single standard deviation of each other, each of them is going to have competencies and expertise the other does not. There are going to be specific skills where one truly is 10x or even 100x the other, but not too many efforts boil down to one specific narrow skill.