Selection bias alert! One can't become a Hitler, Stalin, Mao, Kim Il-sung or Pol Pot without power in the first place, so even if potential megakillers were actually much less common among powerful people we would still expect disproportionately more megakillers among the powerful.
One can't become a Hitler, Stalin, Mao, Kim Il-sung or Pol Pot without power in the first place
I wrote an article for h+ predicting that the rapid fall in the cost of gene sequencing will allow U.S. voters to learn much about presidential candidates' DNA. The candidates won't be able to stop this because:
DNA analysis has a decent chance of reducing political bias by providing objective information about candidates. If, for example, 70% of the variation in human intelligence is determined by identified genes then DNA analysis would reduce disagreements among informed voters over a candidate's intelligence.