• Success on comparatively easy problems in the past, leads to overconfidence on more difficult problems in the future;
• Because people praise you for being good at math or something, you assume you are already wise, and you don't apply your intelligence to becoming wiser in other areas.

Those, in retrospect, were some of the biggest (intellectual) problems I had growing up. I received way too much praise for superficially but not technically impressive achievements, and for things things that were legitimately impressive for my age but which should have suggested that I could have been getting even better. (Not that I'm putting all the blame on the people who were praising me — I should have noticed myself that I could have been learning and improving faster — though since I'm a human with status motivations, I suspect that I mainly just didn't feel a strong drive to improve when the people around me already talked about me like I had magical superpowers, and I had no real intellectual role models to reach upward towards.) I wish I had read "Tsuyoku Naritai" when I was 7. (Well... actually I wish I had read a lot of things from LW and elsewhere as a child.) I often wonder how far my brain might have gotten by now if it had grown up under other circumstances.