Napoleon, actually starved his whole country to fund his war, Hitler killed forty thousand of his own people (not just Jewish people, anyone who disagreed with him), and Cesar was assassinated, because well... not everyone liked him, mostly just the rich people. They didn't really better things for anyone, and after they were killed, any good they did was completely erased.

Dictatorships are generally bad for everyone involved. They're sort of the cultural reset button for countries. People start to think the government should do everything for them, and they let someone control them, and then they get screwed.

Also, every dictator ever, has either killed thousands of people, or tried to take over all of their neighbors, or both. Not to mention the ones who completely screw their country's economy, and end up with people starving.