There also is the fact the popular protests against the regime receive very little to no support from outside.
The West isn't backing these movements, they barely talk about them or engage in meaningful process to further the cause.
Each and every time protests take place, they get repressed. The regime cracks down on them, arrest people en masse, kill them or have them disappear.
Same goes with everything related to women's rights, gay rights and such... usually the West takes great interest in these things. But with Iran? Nope, nothing. A few timid mumbles of indignation, one or two editorials published in some newspaper, and that's it; "we did our part".