The people who left tend were often in a privileged position under the previous regime and the bitterness at having their privilege revoked often echoes through the generations.
They might feign concern for human rights when the regime they hate is violating them (i saw a lot of that when the alleged killing of tens of thousands of protestors) but it's the bitterness of lost privilege which truly drives them.
Ive seen it with Cubans, Venezuelans, Angolans, even the odd Russian.
I have not met a single Iranian expat who was in a privileged position. All the Iranian expats I know are in their 20s and 30s and were just very lucky to get a visa, many in the Obama years. I suppose there were some changes during Obama that allowed more Iranians to immigrate?
For my wife, her family is actually very anti-monarchist. Exactly because of the feeling that there were privileged and unprivileged class during the Shah monarchy.
My wife grew up middle/lower middle class in Tehran and did not have any privileges in life. She was lucky to get a visa to the US, worked 2 jobs + odd jobs all through college to afford it. Constantly scrounging and networking to survive.
That’s why I love first generation immigrants. I think they’re the hardest working, most resilient people you’ll ever meet.