Majority of people do not care, but certain very vocal and very rich people do care. AIPAC, wacky evangelical leaders who believe in end times, national security types who see Israel as paramount to US security in MidEast, etc. They get to influence policy because majority will not push back on their policy because Gaza is an afterthought.

Because vast majority of voters do not care what happens in Gaza.

This has more visibility than Sudan, Myanmar, Congo, etc. But its a problem in a far away land.

So few people (in th US) can wag the dog.