I think that one thing we have to remember is Harry was still a child. He was dealing with things that no child should have to deal with. He didn't have the mental capacity to fully understand what he was doing. Does it make it right? No. But it also doesn't make it right that he had to take on the burden of saving the entire world. I think it shows us what can happen when a child is placed into a horrible situation and bombarded by wrong doings. It's amazing how quickly the evils of the world can consume and change a person.