Wait what? Murdering people and stealing land turned out great for the murderer's ancestors so it's all ok? Not from the point of view of those who were murder

Wait what? Murdering people and stealing land turned out great for the murderer's ancestors so it's all ok? Not from the point of view of those who were murdered. Using that logic - if space aliens came and murdered all the technologically inferior humans and took Earth for themselves, it would be all ok. After all, they are building a more technologically advanced and superior society on Earth for their children.