How do people who say stuff like this process the fact that the Mamdani sweep was often spearheaded by young Jewish staffers — and supported by many young Jews at the rank-and-file level?

As a journalist, I embedded with multiple groups of migrants during 2015-16 "Syrian" wave (only about a third were fleeing the civil war in Syria, from my observation). I even lived in a smuggler's safe house in Istanbul, waiting for weather conditions to permit a dinghy crossing from Izmir to Lesbos. I went into that experience basically an open-borders person and left a restrictionist. Merkel's flinging the gates to more than 1 million newcomers was madness, sheer madness. Even if these were the most aspirational migrants imaginable --- and they weren't, gotta be honest --- the numbers, the cultural distance, and the conditions of European society should've prompted a rethink. But no. Wir schaffen das. I tried to put myself in the shoes of native working classes in the transit countries (the Balkans, Hungary, etc.) and the recipients (Germany, Sweden, etc.). It was obvious that they would experience it as a cataclysm. Even if most wouldn't become victims of crime, this many newcomers were bound to generate acute incohesion experienced at the street, social services, and housing levels, mostly burdening the native poor and those on the lower rungs of the labor market. The engine of assimilation, not particularly robust in most of Europe to begin with, breaks down in the face of sheer numbers. In retrospect, I've come to believe that this was the single worst and most consequential decision taken by European leaders in the 21st century. I don't understand it. I remember @DouglasKMurray telling me at the early stages that the best way to help was in-country, meaning humanitarian assitance in the Middle East and North Africa, not by bringing them over. He was 100% correct.