According to the passage, why do people join groups that practice secondary cooperation?

* Hướng dẫn giải

Dẫn chứng: In secondary cooperation, individuals devote only part of their lives to the group. Cooperation itself is not a value. Most members of the group feel loyalty, but the welfare of the group is not the first consideration. Members perform tasks so that they can separately enjoy the fruits of their cooperation in the form of salary, prestige, or power.