Because "Democracy" in Iran leaves religious nut jobs running the country. I have no complaints regarding the CIA toppling the previous government. That is a big nothing in my opinion.
Jimmy Carter toppling the Shah was a horrible blunder. All he did was light the fuse to a world wide disaster of incalculable horribleness.
A million people are already dead because of Jimmy Carter. The Iran/Iraq war would never have occurred had the Shah still been running Iran. Iraq would never have dared attack an American Ally.
But there would not have been a Shah if our CIA had not already toppled the prior elected leader., which was long before the Ayatola revolution.