there seems to be this belief that the $6n or so dollars that comes Israel's way each year courtesy of the United States is like some sort of straight cash grant.
it isn't. Quite a portion of the aid consists of loans payable WITH INTEREST. Other large recipients of US aid, such as Egypt, which receives nearly as much aid as Israel does, get a far higher proportion of straight no-strings cash.
besides this amount is just the tiniest pinprick on the enormous US budget. It consists of roughly 0.0001% of it. Americans certainly don't seem to be unduly concerned about it. I noticed one poll last year during the Gaza campaign where the numbers dropped compared to normally, but just about every poll I've ever seen on the matter shows that the US public overwhelmingly endorses the USA's support of Israel.
it is not a one-sided "free hand out". In return, the US has a staunch ally with vast intelligence resource. Much was learned about Soviet equipment in this theater during the cold war - including the capture, for the first and as far as I know only time, of a fully functional MiG fighter plane. That alone was probably worth every penny the US has provided to support this fellow democracy.