The fact a leader can be assassinated at any moment by the US probably changes the succession plan slightly... I imagine any potential successor is thinking hard about whether it's a job they actually want.
I'm not saying either view is right, but reducing the Iranian government to irrational religious fanatics is intellectually uncurious and unempathetic.
[1] - https://i.kym-cdn.com/photos/images/newsfeed/002/355/607/670
I'm British, and whilst I don't think my government is perfect (their stance on digital privacy is insane) they are not murdering people, and we can vote them out at the next election if we want to.