How on earth could so many of these people be so stupidly, mindlessly, barmily, unfathomably, unthinkingly anti-Semitic? (In passing, it's worth noting that a lot of support for the maniac came from teachers.)
Hitler's complete divorce from reality in the later years, though, springs from a simple and all-too-familiar source. This is Kershaw describing the origin of the illusions about pretty much every aspect of life in the Reich that dominated policy by 1942: It was a problem that afflicted the entire dictatorship - up to and including Hitler himself. Only positive messages were acceptable. Pessimism (which usually meant realism) was a sign of failure. Distortions of the truth were built into the communications system of the Third Reich at every level - most of all in the top echelons of the regime.
Every organisation should find something worth considering there, especially those who come to believe their own publicity.