This line of questioning will lead you to the proper answer. Let's just say that even a loyal army can be effected if their wives. mothers, and themselves want to throw out a tyrant.
I hope you are not expecting me to answer "it is us" because I sure as hell don't believe that.
Civilized society, since the beginning of civilization, has consisted of two classes: one in which most members were productive and one whose members produced nothing of value but lived off of the labour of the first class, the proceeds of which was taken by force. The second class is the government. In as much as such systems have been the common form of society for at least 12,000 years, I find little grounds for belief that sociities can be expected to have much influence on the form of government that they suffere.