Lee's answer[0] is a good one, and worth a look, but there are other good answers there as well. Andrea Martin's answer[1] just below Lee's is especially intere

Lee's answer[0] is a good one, and worth a look, but there are other good answers there as well. Andrea Martin's answer[1] just below Lee's is especially interesting because it takes an entirely different viewpoint to the question than the typical "intellectual biases" or "networking/superficial social skills" type of answers: "Fail to develop and maintain mutual support systems among mature, benevolent, competent people. Without a good support system, anyone can begin to slide down a slippery slope when they encounter hardship, miscalculate something major, or fall victim to the misdeeds of others." Go read the whole thing. It's worth it. [0] Permalink to Lee's answer: http://www.quora.com/Human-Behavior/What-are-some-stupid-things-that-smart-people-do/answer/Lee-Semel-10289 http://www.quora.com/Human-Behavior/What-are-some-stupid-thi... [1] Permalink to Andrea's answer: http://www.quora.com/Human-Behavior/What-are-some-stupid-things-that-smart-people-do/answer/Andrea-Martin-3 http://www.quora.com/Human-Behavior/What-are-some-stupid-thi...