people don't "quit" in real societies. Though they may kill someone or themselves.
People "quit" all sorts of "games" in real societies, though. They may "quit" particular social institutions, such as a school or a workplace. They may "quit" the social class or cultural loyalties (e.g. religion) to which they were born and raised. They may "quit" particular groups of friends, or "quit" a marriage or family (or be forced to do so).
Title:
Emergence of good conduct, scaling and Zipf laws in human behavioral sequences in an online world
Abstract:
Link:
http://arxiv.org/abs/1107.0392
Popular science interpretation:
Link:
http://www.technologyreview.com/blog/arxiv/26967/