> If the US wasn't selling weapons, Israel wouldn't be able to do what it does.
It's hard to really draw up the counterfactual but I'm not really sure that's the case. But there are many other players here besides just Israel that are helping to ensure that this conflict continues to fester, chiefly Iran.
Without western support, it is quite possible Israel will simply lose and the conflict will go away, leaving a possibility of building a democratic secular state in Palestine that treats people with equality.
It's a fair point to say that the counterfactual is hard to draw up.
I will point out the main reason it's hard to come up with, is the fact that American aid, weapons sales, and diplomatic support for Israel has been so constant and unchallenged over the past several decades that we don't have many good examples of what Israel would do without impunity.