Interesting question. I think that depends on how you define "their people". In some sense, all dictators improved the lives of "their people".

Nelson Mandela for instance made life better for black South Africans, but he's implicated in violence against white south africans.

Hitler made life better for many Germans, especially given the conditions of the Treaty of Versailles.

Turning back to the US, you could argue that those descended from native americans have not had their lives improved by an ugly history of genocide. The US also enslaved people who our citizens today descended from. There was also internment of Japanese-American citizens. And to this day, high incarceration rates for the poor/minorities.