several things radicalized hitler. as a boy, he saw that slavic royalty had a bunch of influence over austrian politics and markets, at the expense of native austrians, and he never forgave slavs for that. later, after fighting in ww1, he (like many others) blamed the media and the jews for making them lose by spreading defeatism back at home while they fought, leading to a reduction in supplies and support. he used to think antisemitism was a silly conspiracy theory for lowbrow men before he started looking into it and noticing. this is a vast oversimplification of course, but it's a decent summary.
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