Change my mind Politics and governments

Slavery and Colonialism were the best opportunities for Africans.

I'm obviously not talking about the men and women who were slaves themselves, but instead, about their descendants and, in general, the African Nation that benefits from the condition left from this slavery.

An unfortunate statement. Result does not justify the cause. In a similar logic, one could say "Holocaust" was the best opportunity for descendant Jews. That would not be a statement endowed with reason. Could you say that as well? If something literally costs "an arm and a leg" - see the Congo example - then we have no right to sit on the top of a "mental patheon" and take decisions on what is best for whom.