I think it's worth pushing back, making sure they know what you believe, and that you have solid reasons for believing it. If they've been on birthright, they've likely been subject to a lifetime of propaganda that places them at the center of a fantasy bubble where Israel's main relationship to Palestinians is charitably bringing them into the 21st century, and only defending itself from those radical Islamist ingrates who agree with Hitler. They don't know what living in Gaza as a Palestinian is like. They can't understand what "right of return" means to those who are denied it. They don't see settlers attacking Palestinians, destroying farms, or soldiers raiding their homes. In their history, the Oslo accords were an olive branch that the genocidal Arabs rejected. By now maybe they know about the IDF's bombing campaigns that harm civilians, but they think this is simply a problem of the wrong party in charge, and it's not like they want to kill Arab children, and anyway it would stop if Hamas weren't in power. Yes, they think a Palestinian political organization has power, in some meaningful sense, in the occupied territories.

I don't know what change's these peoples' minds, but I believe the only thing you can do is be vocal, patient, and firm.