I'd underline the power of disenchantment, which I've discussed previously with reference to the protests against authoritarianism in Chile. At root is a series of broken promises.
1. At the heart if it all is a new sociological type: the graduate with no future
[. . .]
9. The specifics of economic failure: the rise of mass access to university-level education is a given. Maybe soon even 50% in higher education will be not enough. In most of the world this is being funded by personal indebtedess - so people are making a rational judgement to go into debt so they will be better paid later. However the prospect of ten years of fiscal retrenchment in some countries means they now know they will be poorer than their parents. And the effect has been like throwing a light switch; the prosperity story is replaced with the doom story, even if for individuals reality will be more complex, and not as bad as they expect.
10.This evaporation of a promise is compounded in the more repressive societies and emerging markets because - even where you get rapid economic growth - it cannot absorb the demographic bulge of young people fast enough to deliver rising living standards for enough of them.
11.To amplify: I can't find the quote but one of the historians of the French Revolution of 1789 wrote that it was not the product of poor people but of poor lawyers. You can have political/economic setups that disappoint the poor for generations - but if lawyers, teachers and doctors are sitting in their garrets freezing and starving you get revolution. Now, in their garrets, they have a laptop and broadband connection.
This is also much like the reasons Bourdieu gives for France's May 1968. As I put it in Posthegemony:
Bourdieu argues that the May 1968 student protests were the result of ethical self-protection in the face of the inadvertent effects of increased access to the French educational system in the 1950s and 1960s. The expansion of secondary and tertiary education had led to “diploma inflation” and the devaluation of scholarly certification, such that educational success could no longer be converted straightforwardly into social mobility. Yet “newcomers to secondary education [we]re led . . . to expect it to give them what it gave others at a time when they themselves were excluded from it.” Whereas “in an earlier period and for other classes, those aspirations were perfectly realistic, since they corresponded to objective probabilities,” in the wake of systemic expansion “they are often quickly deflated by the verdicts of the scholastic market or the labour market.” The social field had changed, shattering habitual expectation and provoking an ethical refusal that questioned the very rules of the game: “A whole generation, finding it has been taken for a ride, is inclined to extend to all institutions the mixture of revolt and resentment it feels toward the educational system.” Hence the “anti-institutional cast of mind” that “point[ed] toward a denunciation of the tacit assumptions of the social order, a practical suspension of doxic adherence to the prizes it offers and the values it professes, and a withholding of the investments which are a necessary condition of its functioning.” However much the events of 1968 drew “strength from ideological and scientific critiques,” they were not themselves ideological; rather they constituted a suspension of (practical, embodied) belief in the wake of an interruption to the smooth functioning of social reproduction. They were part of an ethical revolt that drew on habitual inclinations to confront the social order. (pp. 220-21)
The only thing I'd add, then, to Mason's analysis is the importance of habit and conatus, the instinct for survival or increase. And it is conatus that builds the multitude.