All modern states are based on four things: myths, laws, ethics and hidden truths.
The first three - myths, laws and ethics - are taught to everybody and driven through social institutions that condition individuals to be good members of the collective.
The fourth - hidden truths - are not for general consumption because they render the first three false. Once these hidden truths are understood by the masses, the myths, laws and ethics they were taught can no longer control them, and they look for new myths, laws and ethics to sustain them.
Civilizations "collapse" because elites who know the hidden truth ultimately cannot help themselves. The ethics created to bind the masses do not control the true elites, and this fact ultimately leaks out as the true elites become brazen in their hubris and begin openly breaking the laws.
Once the masses realize that the laws and ethics of society only bind them and not those who truly rule, the masses begin to question their myths.
And that is when all hell breaks loose.