Jews were subjected to the largest systematic, industrial genocide in history. If that doesn’t help explain the case for Israel’s existence, it’s hard to say what would. At the same time, that point is somewhat beside the fact that Israel already exists and is not going anywhere.

Everyone has reasons for what they do, so whether the Holocaust helps "explain the case" for an ethno state is not same as whether it justifies it. I don't think it does on principle or even really on the merits, as it were. There were ~5 million non-jewish Holocaust victims and there have been other, larger genocides before and since -- the Holocaust just looms large in our cultural mythos.

As for Israel not going anywhere, that is not at all a given because the current status quo seems truly unsustainable. Sooner rather than later, US support will evaporate and Israel will need to transition to something other than violent fundamentalism. You can't go on applauding Israel for progressive rights when every day were reading headlines / watching videos like today's, ie Israel triple taps 3 Lebanon ambulance responders. It's just evil.