Who decides something is right or wrong, good or bad?

In most of the history textbooks, they describe Adolf von Hitler as the crazy, super evil Nazi leader that started World War II. Really? It is the complete reason? The Nazis could not gain power so quickly without any reasons. I believe one of the most important reasons was Germans were starving, and they needed someone who lead them out of starvation. Why they were starving? Part of the reasons is the post World War I punishments on them which were decided by the Allies. In other words, the Allies from World War I were the one who indirectly started World War II. Hitler might be crazy, because what he had done to the Jewish people during the war, but he successfully led his country out from poverty when other capitalist countries were slowly recovering themselves from the Great Depression. In that sense, he was not a complete crazy bad guy as the textbooks were trying to tell. But I am not trying to argue what Hitler did to the Jewish people were right, but look at what Jewish people had done to Arabs after World War II. Things Jews had done to Arabs are no much better than what Nazis had done to them. They kept on taking over land from Palestinians, not caring whatsoever about Palestinians, pushing Palestinians to the sea. Did American government, who often claim itself to be the peace keeper in the world, do anything about this at all? They were the ones who granted Jewish people their land on Palestine through UN of course. They were the ones who always support Israel during the wars. They were the ones who connived Israel to have nuclear weapons. Aren't those things considered to be wrong or evil? But who cares? As long as Israeli and Americans kept winning the wars, taking others' land, and the history books will write whatever they want people to read. Who decides something is right or wrong? Whoever has the power.