It is an interesting thing through in your comment. Once historical person is morally bad, the person just can't be skilled or good at something - success must be coincidence and luck. ThE same way as people get angry if you say that Hitler was not all that bad painter.

That is just not how it is. Murderous psychopath can achieve success due to talents and hard work etc - neither makes him less guilty.

What makes Stalin or Hitler intellectually interesting are their tactics and abilities. The next succesfully murderous dictator will have them too. Else he would just stayed violent young man.