It's a little more than the bread and circuses.

Most of our people don't resort to murder or violence to settle their matters. This is a product of living in a world that once held civilization to a standard that it was capable of resolving those disputes adequately. Thus the reason for law and the expectation of order. At some point that falls apart and people resort to their instincts. When the expectation of the Law to keep things ordered and Just fails, then it falls apart.

You will find that all of a sudden, people will be very eager to collectivize among their in-groups.