A qualitatively better hypothesis would be "Everybody knows Mensans are insecure". I never met any Mensans or Prometheusians at Stanford that I knew of or cared

A qualitatively better hypothesis would be "Everybody knows Mensans are insecure". I never met any Mensans or Prometheusians at Stanford that I knew of or cared to ask about, and this included IITians with MD + CS PhD's. The ones I ran into outside of academia were heavily leaning on the neuroticism side of Big 5. This may not be a completely fair assessment as a generalization, but it seems like an approximation of a fair amount.