Two things;
A) Iran isn't just Israel's problem. Israel has the most to lose, but Iran is also the problem of France, the UK, Germany, Spain, Italy, Canada, Finland, Saudi Arabia, UAE, Egypt, Jordan, Turkey, etc. etc. etc. and yes of the United States of Death to America as well. So trying to present an hypothetical declaration of war on Iran as "going to war for Israel" isn't honest.
B) The American foreign aid to Israel, which makes ~1% of Israel's GDP, does not somehow remove Israel's sovereignty as a state. America supports Israel militarily and diplomatically because the two nations share both values and geopolitical interests. The relations are clearly asymmetrical as one nation is the biggest empire on the planet while the other is a tiny nation of 8 million souls, but that doesn't mean that the US "doesn't get anything" from it as you've previously falsely claimed. Just to name one field, the Israeli-American cooperation in military research had seen a lot of successes and many of the systems that American soldiers use on the battlefield are the product of Israeli scientists, or have Israeli-added features in them. To conclude it's false to portray the Israeli-American relationship as something that isn't benefiting America, and if it was true there wouldn't be any relationship to begin with.