of course that's not USA's problem with Iran, it's Iranians problem. it's an impossibly difficult problem to solve, and the more economically stable the regime is, the more resources they can spend on their survivability. Saudi Arabia will probably never have a chance to overthrow, they have too much resources to detect and squash any resistance.

Iran on the other hand is in a unique position of instability that they just might have a small chance of brighter future, small chance that will end the moment the sanctions will be lifted.

maybe because SA doesn't threaten US allies as much as Iran