Your post is hilarious.
"when they invaded Europe" - They started in Europe, they didn't invade it.
"BUT that's not a good reason to invade other nations." - Says you.
"But in the scope of reality, most things are just right and some things are just wrong, whats right is right & whats wrong is wrong." - Incorrect. There is no universal morality.
To massively simplify:
Have you ever gotten mad at someone and taken aggressive action against them? That's what they did. The German populace, for the most part, came to believe that much of the rest of the world was out to get them and owed them something. In fact, the debt was so large and the threat so dire that war was a necessity to prevent things from getting worse.
So far as they were concerned.
You might say that they were wrong, but that isn't relevant to this point, what is relevant is that they thought they were right at the time (and many never changed their mind about that, or even admitted accepting it in the first place) and people make decisions based upon what they think is right.
There were a lot of things coming out of WWI that really helped set the stage for WWII and it would assist you a lot to understand the rise of Nazism if you studied Germany in the aftermath of WWI.
Also, in general, most people are just tools.