The biggest justification for regime change not ever mentioned by any self promoted "Iran expert", is the "We broke Iran, so we have to fix it." one.

In 1979 the US screwed up, when it stood down the US trained Iranian military leadership who had made quite good preparations to temporarily take over, while the Shah addressed his medical emergency. Their plan was beautifully simple. Stop Khomeini's revolution.

This stunning error by the US, resulted in the completely avoidable American embassy takeover and biggest embarrassment, the hostage crisis. The US broke a beautifully pro-US country, combined with yet another US mistake of Saddam Hussein, and plunged the region into the deadliest and longest war of the 20th century.

The sheer US ineptitude resulted in the creation of the first ever fully Islamic State. Who succeeded in taming specifically the US, but Western civilization in general, including effectively neutering Israel for 4 decades. Culminating in the worst atrack on Israel. Ever.

The cascade of Islamic extremism that followed the US betrayal of the Shah's partnership, friendship, and unquestioned loyalty, immediately inspired Osama Bin Laden to demand the US pay him back for his proxy fighting help getting the Soviets out of Afghanistan, by giving him his own Sunni version of Shiite Iran. When the US declined and worse, tried to take him out, Bin Laden got even with 9/11.

And the rest is really awful history.

To stop the ongoing nightmares, the US has to click it's ruby slippers and return to Kansas again, by quickly deciding to fix Iran now. Before Iran atomically decides the darkest future for everyone.

Hurry up.