You’d have to get up pretty early in the morning and work very hard all day if you aimed to kill a few million single-handedly by the end of the day. No, that won’t work. You have to persuade a whole lot of other people to do the slaughtering for you. Meaning a lot of people have to think you are a pretty neat guy and they are lucky that they get to do the great work you command them to do. Mass murderers have to be dictators because otherwise you can’t murder that many.
Lenin, as Stephen Kotkin says, is the gold standard in brutal dictators. Here’s Kotkin in conversation with Peter Robinson. A brilliant video.