De tocqueville noted that both french and german peasants had lived in poverty, but only the french peasants overthrew their king in a revolution. the reason, de tocqueville said, was that the living conditions of the french had been improving, while those of the germans had not. improved circumstances can fuel human desire for even greater advances, according to

relative deprivation theory

In the case of the French Revolution, it would also be good to note the role of relative deprivation in regard to the bourgeoisie, who were also instrumental in starting the Revolution.  The bourgeoisie had been gaining wealth through trades and commerce, but were denied the same political status as the nobility.  Nobles enjoyed tax exemptions and had political influence, while the bourgeoisie were still considered "commoners" of the 3rd Estate whose social rank was the same as peasants.  They saw themselves as being as wealthy (some more so) than nobles, and as being equally as intelligent and valuable (if not more so) ... and so were spurred to revolution to gain the political advantages that they saw the nobility enjoying.