If one remembers that most of America's Jews had grandparents or parents who came from either Germany (Marxism oriented) or Russia (Communism oriented) there remains only the pressing question of why teh continuing love of socialism?
IMHO, it is simply something absorbed while growing up. Oops - make that getting older but no wiser.
I've given a lot of thought to the general question of Jewish leftism over past years, since it's an area of personal concern. There are some pertinent comments on the thread, especially #35 IMO.
A large percentage of American Jews came here as leftists and have handed down the traditions of leftism from generation to generation, just as other Americans *used* to hand down our traditions of individual freedom and personal liberty. My opinion is that one of the reasons that American Jews have clung to leftist traditions so doggedly for several generations is simply because they were excluded so long from so much of American society. But now that society is open to Jews, I have hopes that the traditions of the left will be abandoned and those of freedom embraced. I tentatively believe that is now happening.