Iran is "vulnerable" and "weak"? Really? It just took out a $750M E-3 Sentry AWACS using missiles and drones that probably cost it a total of a couple of million bucks. It downed an F-15E and an A-10. It damaged a Black Hawk helicopter.
The stakes for the Islamic Republic regime are existential. If it survives, it wins. And in the entire history of warfare, the number of regime changes achieved via air attacks alone is precisely: ZERO.
That means boots on the ground. In a country of 90 million that can probably rustle up 1 million troops to defend itself. You really think the USA is going to go there?
The end result will be the survival of the Iranian regime, which over the next 5-10 years will rebuild its missile and drone capabilities and probably double down on building nukes. And it will never trust the USA again, having been attacked while in the middle of negotiations.
Meanwhile, the USA has a significantly depleted Patriot arsenal and other weapons and is going to suffer enormous economic shocks. And Russia's loving the increased oil prices (except thankfully, Ukraine is hitting its ability to export oil, but still... it will end up benefiting Russia.)