Cubans kept massively supporting Fidel for quite some time, and quite explicitly, even through the disastrous Communist economic policies.

Iranians keep protesting; last few years have seen several large protests, involving hundreds of thousands, and continuing for months. The popularity just isn't there.

Regarding revolutions, it's quite often that a relatively small group of like-minded people capture the control, and the majority is weakly supporting them, or is even weakly opposed but complies. The French revolution was mostly about some nobility wanting to remove the monarchy that oppressed them, along with the rest; most of the population wasn't overtly anti-monarchy, and not even covertly so, but it did not like the monarchy's pressure either. The Russian revolution was "communist" and "proletarian", but even by their own Marxist accounting, proletarians were less than 10% of Russian population, and communists, much fewer still. Nevertheless, they subdued most of the Russian empire.

The Iranian revolution was also done by a group of highly religious people who were fed up with the shah's secularization reforms. The shah, AFAICT, was a guy a bit like Putin, or Saudi kings: efficient and geared towards prosperity of the country, but quite authoritarian. The fact that e.g. the educated urban population in Iran wasn't happy about authoritarianism does not imply that the same people were (or are) huge fans of theocracy. Actually, the theocracy ended up even more oppressive.