>at a cost you are willing to bear.

It's pure greed. The IRGC relies heavily on oil money for funding the massive militia (hundreds of thousands of Basij) that allows it to stay in power; if that income collapsed then it would eventually lose control. Trump however not only refused to bomb Iran's oil infrastructure but even stopped the IDF from doing so, just because he thinks he'll somehow be able to take that oil for himself and his cronies in future like he did in Venezuela.

I don't think that's true. The Khomeini clan do rely on IRGC to remain in power somewhat, but it also has strong influence towards the civilian government, and the OPA it ran on the Mullah at the start of the war, getting a non-mullah elected supreme leader at a very cheap price prove they rely on more than their central militia. A lot of the clans who supported the Shah during the original coup also seems to support the regime, which makes the north stable. The western part of the country, despite insurgents/independence groups, seems to have reported their hatred of S.Hussein towards the US (to be fair, the chemical weapons Hussein used to bomb their village were from the US), which means they might choose to fight the US rather than the regime.

Imho the regime was made stronger because of this war. It was really a bad moment to strike. Khomeini had a cancer, and waiting for his death and the succession crisis that would have ensued would have been a better choice. Now the regime is stronger than ever.

Although my real thoughts is that this strength the Khomeini project is temporary, in the sense that the only reason the regime lasted this long before was because the power was shared. If they keep pushing for more control, without sharing, they will end up loosing everything.

I don’t think that’s it. Iran has demonstrated an ability and willingness to strike the equivalent infra in the gulf states, including the very vulnerable gas liquefaction facilities in Qatar. If the US destroyed their oil infrastructure, all that infrastructure goes. Hormuz would be irrelevant, there’d be almost nothing to ship through it. Plus given the long term reductions in the gulf supply already from damage, the world now needs Iranian oil.

That’s why Trump has allowed Iranian oil already outside the gulf to be sold, was willing to drop oil sanctions on further Iranian shipments, and was so panicked when Israel hit an Iranian oil facility.

Bombing Iran's oil infrastructure would give Iran the casus belli to do a like for like strike on the GCC countries. Imagine strikes on Fujairah port, the Aramco, ADNOC and QatarEnergy refineries on the Gulf Coast, as well as the Yanbu and Habshan pipelines.

That means effectively taking out 25℅ of global oil supply -> oil at 150-200 a barrel -> Trump and the Republicans lose the midterms badly -> Trump gets impeached. I'm sure somebody explained it to him that this is exactly what would get happened, which is why he did not overextend or let Israel do so.