One thing that I find interesting about this is that "samurai lived in dignified but extreme poverty" but never really did anything to threaten the state and take its riches for themselves for hundreds of years, despite all of them being crammed together with lots of opportunity to organize an enormous rebellion right in the city where the king lived.

Perhaps they didn't think of it as poverty. Anyway, great read.

I suspect that, in reality, it is the indignity of poverty which motivates people to take up arms against each other. So long as dignity is retained, poverty may be emotionally bearable (perhaps to the point of actual starvation, when dignity becomes unsustainable).

They very much understood their situation. That was the means of control. Their incomes were directly defined by agricultural productivity, and their expenses largely controlled by the shogun. Daimyo couldn't meaningfully communicate with each other, easily intermarry, or form alliances. They were forced to maintain huge retinues and lavish estates, and the shogun could bankrupt them or kill their family at any point.

The shogunate needed to do some balancing along the way (including the introduction of metallic currency), but the government had enough levers to keep the samurai in line, right up until they couldn't.

Looking at rebellions and revolutions in Europe (just because I know european history better than asian history), they tend to start when someone (not necessarily the poor) feel than the upper class/the king is not doing what it's supposed to be doing. It's not a cash grab, and in a lot of revolt what the rich have and don't deserve is not taken and distributed, but rather destroyed to show that it's about punishing traitors of the social contract, not robbing them.