Nire Bryce

Maybe in an environment where most people show overconfidence about their abilities, people expect overconfidence, and will think less of you if you don't show it. Which makes it more likely that people who wouldn't otherwise show overconfidence would now show it, feeding the feedback loop. And of course people will compare themselves with the level of confidence that others will show, leading to people (especially people with self-esteem issues, or who are told are less capable, or who feel like outsiders...) feeling like a failure when they aren't.