Selfish behaviour only works because the rest of society on aggregate are still contributing to the maintenance, development, and research of a multigenerational civilisation.
A society in which almost all are working not out of pure altruism, but out of necessity to satisfy their own selfish needs.
I don't believe it's very selfish to want to avoid starvation and to have a roof over your head.
Selfish behaviour only works because the rest of society on aggregate are still contributing to the maintenance, development, and research of a multigenerational civilisation.
And those people only make those contributions out of a selfish desire to keep their environment from changing and for their own self-satisfaction of "making a difference".