Baumeister and his group wrote in the social-exclusion paper that being part of society means accepting a bargain between you and others. If you will self-regulate and not be selfish, then you get to stay and enjoy the rewards of having a circle of friends and society as a whole, but if you break that bargain, society will break its promise and reject you. Your friend groups will stop inviting you to parties and will unfollow you on Twitter. If you are too selfish in your larger social group, it might reject you by sending you to jail or worse.