4.  Why the incompetent don't know they're incompetent

While our thoughts are on darker matters, here's a quote from Bertrand Russell:

 "One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision."

The simple reason is that the incompetent don't learn from their mistakes. Even telling them seems to make little difference. Unfortunately talented people also tend to underestimate their brilliance. Could this partly be why society doesn't change?