Talk of "regime change" in Iran was among the biggest delusions. Along with that goofy ass "This was Iran in 1979" propaganda video circulating that attempts to undermine the significance of the 1979 Iranian Revolution, the year of a popular uprising, where the people got rid of the US-backed puppet, Mohammad Reza Pahlavi, the Shah of Iran (proceeding the 1953 Iranian coup d'état, orchestrated by the CIA and MI6, which overthrew Prime Minister Mohammad Mosaddegh). The U.S., U.S.-backed Israel, and the West have been geopolitically pissed ever since.
The US-backed Shah of Iran, Mohammad Reza Pahlavi, was overthrown by popular uprising due to authoritarian rule, corruption, unequal distribution of wealth, etc. So, of course the "this was Iran in 1979" video doesn't tell the whole story. So, Iran already knows what "regime change" feels like from the West, highly aware of their nation's history, and unlike the U.S., is not trying to go backwards.