Not least because, from his earliest street-fighting days and throughout his subsequent career, Hitler's enmity was directed above all to Bolsheviks and Marxists.
that and some other peculiarities he had..maybe just plain old psychotic resentment
when I was a boy 20 years after the war the conventional wisdom was he had to pick someone...a target group...I never believed that
he really hated Jews viscerally and used his power to act on it..and he didn't just decide to go kill a few million of them for political strategy.