This is it. Relative economic prosperity, at least as long as it's somewhat widely distributed among a large proportion of the population, usually seems to be quite helpful in smoothing over any roughness of the general political situation for most. In any place, one might disagree ideologically with the way certain things are unfolding politically, but people will usually be much more likely to accept it so long as their material situation is improving, be it real or perceived. Of course, if that economic prosperity or general perception of it goes into decline, the situation can suddenly become quite ugly politically.

Definitely true, not something that can be applied elsewhere.

There's also a silencing effect if you're in a good quality of life that you don't want to potentially risk that by being annoyed about some aspects of society.

I think that applies to China and it applies to Iran. And you can see it in other countries where they have no policy change, but due to outside reasons the quality of life decreases and people start demanding policy and regime change.