Because I don't know what the motivations of the Jews who want to replace the Arabs in the West Bank and East Jerusalem with other Jews are. Nor do I know the motives of the American Jews who are funding right wing extremists in Palestine are. After all, there are "atheist" Jews here who support these Jews as well.
They believe that all the land in Israel, including Palestinian land, should rightfully be available as a Jewish state. I'm surprised you have not worked this out, given how often and how much you comment on such matters. In Palestine, or in Israel? Either way, their motives are most likely very similar. That's probably some kind of deep-seated racial hatred, I'd guess. When I find perhaps more disturbing is the American Christians who support radical Zionism because they believe in and wish to hasten the "end times" predicted in the bible. These people want war and destruction because they believe that then Jesus will come down and carry them all away to heaven. Religious fundamentalism in all its forms is dangerous.
You realise that the religious Jews who read the Torah oppose Israel as a heresy? Israel is a secular achievement, not a religious one. If you read the history of the zionist movement, you'll see that the rabbis have always been opponents of the state. http://www.jewsagainstzionism.com/rabbi_quotes/index.cfm