I'll take this as a serious question.
The usual caveats. I am no military man, nor do I claim in depth experience. I expect
@Red Leg can jump in to expand on or correct my points.
However, I do know that Iran is a country of nearly 100 million people. They have a relatively rigid, authoritarian government with a strong grasp over the local populace. They have a relatively strong military in the same sort of ball park as Australia, Pakistan, Canada, Spain, Egypt. They have a decent GDP and are at least trying for nuclear capability. They are not Somalia, or Iraq or Afghanistan.
They also have a lot of support (tacit, if not explicit) in the Middle East, and if their combatant was the US, many others would pile in as well.
All that to say, the US can curbstomp them. But to achieve anything other than pissing them off, increasing their support in the region and an uptick in activity against US interests, would require a real, boots on the ground war. Not a simple bombing run, not a counter insurgency operation, not a light touch peacekeeping operation, not even just cruise missiles and a carrier group. A real, American servicemen in the face of fire, conflict of a greater magnitude than any previous Middle Eastern operation.
If you want to 'solve' the Iran problem, you're talking more effort and casualties than Korea, than Vietnam, than the entirety of the Middle East misadventures of the past 30 years. Years and years, billions of dollars, 100,000s of US servicemen in a war zone, extensive terrorist activity and thousands, likely tens of thousands of deaths. You'd win, no doubt about it, but this is not a walk in the park and it will cost lives, treasure and materiel. If this is the spark that gets them into the nuclear club (and you can be sure that'd be priority #1 if the US tries anything decisive) this could be a serious threat to any US asset within their missile range, which includes Isreal, Egypt, Oman, Saudi, the UAE, Turkey, much of Eastern Europe. Maybe even places like Greece or Italy.
Then what is the end goal? You invade, you win, you depose their government. Then what? Constant occupation in the same vein as Iraq until someone gets bored and we're back to square one? The people there are not of a culture that will readily adopt a western democratic system, or even be pleased to see US troops on the ground. It'd take at least a generation, probably two to make that stick. Does the US have the political will to occupy a hostile territory for 50 years to achieve it? Based on the failures in every other Middle Eastern nation in my lifetime, I think not...
It's easy to talk a big game, but this is one that whilst absolutely winnable, is an option that will be hugely expensive, and one that there absolutely isn't the political will for on either side of the aisle.
Make up your minds.
