A member of Zohran Mamdani’s mayoral transition and top fundraiser for his campaign once celebrated vile anti-NYPD chants and called for America to be “punished for its sins,” The Post has learned. Jack Gross, a far-left activist with deep ties to the New York City Democratic Socialists of America, repeatedly espoused far-left ideologies online and even praised Karl Marx, the 19th-century revolutionary who helped found communism. Gross, who helped raise more than $20,000 for the Mamdani campaign, wrote on social media in June 2020 that it was “beautiful” when New Yorkers yelled “NYPD suck my d–k” — a common refrain...