The reasons given here for anti-Semitism and the Holocaust are usually the non-falsifiable claims that if Jews became more secular and involved in the outside world then it leads to more anti-Semitism and persecution. Of course, this claim is never rigorously tested or subject to any critical scrutiny. What about Sefardim who were becoming more secular due to the Alliance but were not subject to the Holocaust? Were Jews becoming more secular during Tach vTat? What about the vast majority of American Jewry who was pretty secular since they came over from Europe yet lived and continue to live in relative peace?
The whole claim is just cherry-picking examples that work well with the preconceived notion that punishment follows more secularism. It’s not a strong rigorous claim.