Flawed Perception

I struggle with people who have disproportionately inaccurate mental representations of themselves. I find myself up against a barrier when attempting to relate to individuals who think themselves to be geniuses despite all evidence to the contrary. I can't connect with people who believe they have all the answers, but often supply superficial opinions in response to factual inquiries. I don't understand why wildly popular artists think that they have no skill. I am frustrated with smart people who routinely tell themselves they are dumb.

What's the deal? Why is it that some people are completely blind to their flaws, and others can't see their strengths?

There's the obvious exception for those who have had their beliefs repeatedly reinforced throughout their lives. I get that. It makes sense that self-esteem would be low when others have repeatedly devalued a person's worth. I get the inflated ego of a person raised by a self-esteem junkies.

What I can't figure out is those who fall outside of these categories. The people who had relatively typical upbringings. They had mixed successes and failures. However, the experiences that contradict their self-image were chocked up to luck or external influences. Their confirmation bias allows them to completely ignore that this is not a unique moment in their lives. Do they not see the common threads that point out errors in their judgment? Can they not understand praise/criticism?