I don't wholly disagree with you. But I think your view is similarly un-nuanced. There's a large minority of Christan Conservatives in the US who, at present, care deeply about Israel. Of course, a lot of them support it for quasi-theological reasons and not for any love of the Jewish people per se. But they still support it. Moreover, a lot of Americans (particularly but not exclusively on the religious right) perceive their country as inherently at war with the Islamic world. My enemy's enemy is my friend, as the old saying goes. And, finally, a lot of Americans like to see their country 'hanging tough'. Being pro-Israel is part of that package or, at least, has been up till now. It's all sentiment at the end of the day. If it weren't for that sentiment, the guys at AIPAC would have nothing to exploit and no US politician would have to worry about them. Because it's all based on sentiment, Israel can't afford to offend against America's sense of itself as a great power.
Hamas says Egyptian mediation has restored calm along Israel, Gaza border (Haaretz)
from the article: Israel can't decide its value to the U.S.