Everyone knows the names of the famous dictators or rulers who killed millions of people, but the vast majority of people have never heard of, for example, Norman Borlaug, Yuan Longping, Dr. M.S. Swaminathan, Vasily Arkhipov, Maurice Hilleman, Abel Wolman, and Tu Youyou, despite many of these people each having cumulatively saved more lives than these famous dictators killed. You can argue that their inventions/campaigns/actions would have existed without them specifically, and authorship belongs to large-scale collaborative scientific efforts, research building on previous works, etc., but you can make a similar argument for the dictators, that they are merely representatives of broader historical events.