4 ideas
Kapuściński places the start of the revolution in this moment. Authoritarian power depends on individuals routinely performing fear, and once one visible person stops, the shared calculation behind obedience collapses faster than any organized opposition could force it to.
When a dictatorship destroys parties, unions, the press and independent associations, opposition has to flow through whatever institution it cannot afford to abolish. In Iran that was the mosque and the clergy. The revolution therefore inherits that institution's language, leaders and goals, even among people who never wanted a religious state.
The Shah's 'Great Civilization' imported factories, weapons and luxury goods without the skills, infrastructure or social consent to absorb them. Much of it rotted at clogged ports, and the wealth went to a thin elite. People who feel humiliated by modernization imposed from above protect their identity by clinging harder to tradition, which turns the old customs into a political weapon against the modernizer.
Over decades of rule, a despot eliminates or exiles independent thinkers, capable administrators and potential rivals. He keeps only flatterers and the mediocre. When he falls, no competent class remains to govern, so the society's most organized and least tolerant faction fills the void.