They were not "doing well." The Shah was a dictator who crushed dissent. He was put in by the US and the British which destroyed a secular democracy in 1953 using fanatic religious clerics. As in many other countries, Western imperialists nurtured Islamic fanaticism for their own ends.

@Krish55 They were installing telecommunication equipment to unite the country, women had access to western ideas and education. Within a few decades, they'd have entered the ''modern'' world...and THAT is what set the fundamentalists against him.