Even then, there are Jewish persons who advocate for both Israel's existence and the humane treatment of the Palestinians. There was a Jewish Palestinian rights activist and Holocaust survivor in St. Louis named Hedy Epstein who died a few years ago. I had the pleasure of meeting her, and she was a truly beautiful person. I can't recall the intimate details of her beliefs, but I don't think she advocated for the complete dissolution of Israel.
https://en.wikipedia.org/wiki/Hedy_Epstein
Also, I can't speak to the actual incidence of these types of persons or whether they are just a boogeyman for Jewish Americans, but I had a Jewish friend in law school that believed that the passionate support for Israel by antisemitic persons in the South (think Roy Moore and that ghastly "Bernie Bernstein" faux robocall) stemmed from persons who wanted Israel to succeed so that Jewish American would leave and go there.