Every society and civilization collapses for the same reason: the people in that society start to place self-interest and partisan interest over the good of the society as a whole. Your post couldn't be more self-contradictory.
The entire point of libertarianism is to reject the notion of collective responsibility.
According to libertarian philosophy the concept of "society" is an artificial construct invented by collectivists - libertarianism postulates that there is no such thing as society. There are only individuals pursuing their own individual interests in a rational manner.
While smoking as much pot as possible, of course.
Plz the charge that all libertarians are potheads is lame. Prohibitions are stupid, ineffective, contradict the entire idea of self ownership etc. Acknowledging this reality doesn't make you a druggie yourself. Now as for his point contradicting libertarian philosphy I already pointed that out.