Democracy is, I agree, a good thing, but I don't think it fixes all of this world's problems.
About Hitler, there was, and is, a lot of propaganda about how the US was forced to join to save the world. Some is true, and some isn't.
But I have studied WWII in detail, and I am pretty sure that Hitler would have been defeated without the US. I am not saying he was not a threat, or downplaying his power, but when the US joined, the war had progressed to a point where (in my humble opinion) the German army was doomed to fall to Russia. Hitler had attacked Russia, and was stuck there into the winter, which destroyed much of the Soviet army.
and why is that?
(I do want to say that I am actually American, although I live overseas)