Israel is a military toehold in the region. Israel desperately needs our help, so we help Israel because it allows us to have someone who desperately needs our help in the region.
Without US money there’d be no Iron Dome. There’d be no Israel of any kind. Israel needs the US, and that is why we chose Israel as our local ally.
From Machiavelli’s The Prince:
The Romans, in the countries which they annexed, observed closely these measures; they sent colonies and maintained friendly relations with[2] the minor powers, without increasing their strength; they kept down the greater, and did not allow any strong foreign powers to gain authority
Considering a selfish, manipulative, ahem Machiavellian worldview, the reason the US supports Israel is because Israel is the local minor power, which can only become the local major power with our help.
With US help, Israel is on top over there. Without it, Israel is a minor power. That is why Israel, specifically, gets our military investments.