I think my weirdest characteristic comes from being really really successful at formal schooling in a family that held it as the main value. Because my experiences in education have almost exclusively been easy top-tier success, I entered adulthood with an air of effortless invincibility that has been both out-of-line with some practical life skills and has also led me to take big swing-for-the-fences risks in the course of finding my place in the world.
So far those two vices haven't collapsed into a single crisis (where I get fucked by lack of a life-skill while out-on-a-limb) buuuut each of them has separately caused crises so it's probably just a matter of time. I've got to start upskilling before I bring irrevocable disaster to the people around me. And I think I need an education on risk.
Incidentally I feel like this kind of Alcibiades character should have been the Peter Wiggins backstory: that he was a really gifted kid in a brainy family, a childhood without struggle messed up his prudence, and his conflicts with resentful people gave him a shit dynamic with most of humanity.
If this were the case, though, then the torturous treatment of Ender would be justified by his family history. And it's hard to see how Valentine works in this.
Oh and BTW having a lot of unearned confidence is pretty good for most socializing but there's a population that fucking hates it and will prize shoving you around a bit.