They aren't really dollars, so much as in-kind aid. The US pays Raytheon to manufacture interceptors in the US and then send them to Israel. So it's fungible in the sense that without US military aid, Israel would have to figure out how to pay for missile defense and other military needs. And maybe that involves less domestic spending on healthcare and maybe it involves making deals with other countries or making foreign or military policy changes. Maybe it leads to positive changes like peace deals, but maybe it leads to negative changes, like Israel switching its allegiance to countries that aren't as friendly to US interests.

Ultimately, the person I'm replying to is giving a false impression of what the US is doing.