This is what I understand of history from reading stuff and seeing it happen again.
Hitler was a Fuhrer (which means "guide" in German) and wanted to take over the world because some people like that kind of thing.
At the time, Germany was in deep doodoo financially, to the point that people were having to buy wheelbarrows to take their pay home, the Deutschmark being worth less than the paper it was printed on. And the wheelbarrow was worth more than the pay.
When this happens, folk turn to anyone who can offer a "better" solution to their problems than the people currently offering a solution.
But, in order to unify the people, a Fuhrer had to find someone to blame. In America it was the black folk, otherwise known as N......s.
Hitler didn't have access to enough black folk on which to blame the country's ills. He could've gone for folk with moustaches, chaps who wore hats, gay folk, actors, drummers or bus drivers, but again, they didn't number enough to really take the blame.
Poland is a big country. And it's next door to Germany, and pretty easy to invade as well. And it was full of, guess what, Jews!
And Jews tended to run banks, and were well-known (and have been throughout history) for being money men. And the problem was money. So, clever old Hitler twisted the plot a bit, convinced all the folk that the Jews were the problem, got "elected", then realised that he'd pointed the finger and now people expected him to act,
I don't think Hitler could've believed that the Jews were the problem. But he was a convincing bastard, and I suspect his Generals did. And they all went Heil Hitler, mein Fuhrer, and got stuck in.
After that I think it just got out of hand.
That's how I see it. This isn't fact, I'm not a historian. Nor am I anti-semitic. It's your nose, not mine. Wear it with pride.