The glue for all communities is need. The less you need others, the less you need to compromise for others. It is a double edged sword though, on one hand you want the resiliency and security a tribe provides in order to make the gamble that can lead you to succeed, but on the other hand, individuals always have a goal of freedom and power for themselves so if they succeed they will no longer need the tribe (or at least as much), and hence there is no longer incentive to compromise for it.
