World War One had a lot to do with that. Germany was literally ruined at the end of WW1 especially after the decisions taken against them at the Treaty of Versailles where the Allied Nations had laid the rules down for massive compensation on the destruction they had caused throughout the occupied territories. There were many other demands which included that Germany hand over 10 per cent of their Territory, disarm (for instance they were not allowed to have an air-force at all) and that the Royal family abdicate. However, worse was to come, the Allied Nations demanded that Germany detach themselves from Austria.
It had been expected by Germany on a reasonable level that Austria would be allowed to unify with Germany, not so. In fact, the Allied Nations refused to even bring up the subject. That meant that Germany lost Austria and the insult was too much to bear.
Hitler, having become head of the Nazi Party in 1921 was getting nowhere. His idea to re-establish National Honor and prestige was blame the Jews for Germany's economic ills. With Germany being in dire straights having to repay billions in reparations especially toward France and Belgium with a country that is principally bankrupt it did take long for the German people to lend a friendlier ear toward Hitler and his outrageous racial garbage toward the Jews and any other Political Party that stood in his way.
The Coming of the Third Reich ....................................... Richard J. Evans