Frankly I don’t like the “but we could be spending this better at home” argument because the people making that argument invariably would refuse to actually do so, and instead just give out another tax cut.
That money would never end up going in to a single payer healthcare system, SNAP, education or building out more sustainable infrastructure. We don’t do these things not because we don’t have the money for it, we don’t do these things because they would undermine the influence of large financial and corporate interests.
There is a much better argument to not fund Israel, and it is that they’re attempting to ethnically cleanse the Gaza Strip, have flaunted all of the treaties and agreements they made for near on 20 years, and they’re current leadership was undemocratically put in power.