If you overthrow one autocrat and the society is not ready to self-govern, you'll just have another one taking his place. The best you can do is to fund some kind of democratic opposition on the ground and in exile, hoping to grow a political class mature enough that they will take over after autocrat loses power one way or another.
If I were living in brutal dictatorship that has majority support (that’s today Russia) I’d really want foreign powers to „meddle”. But an average Russian likes the current state and hence hates any foreign attempts at influence.
Btw, Iran does have an opposition group in exile in the US, and nobody is trying to reinstate them. I'm not saying they should be, just that Trump's talk about changing the govt in Iran isn't in good faith.
