Imagine there's a lake with 100 fish farms. Each farm operator can pay $50000 to install a pollution scrubber that benefits every farm operator by $1000. Obviously, none of them do it, since it'd cost them $49000.

Coordination problems are why we have a government. It mandates the pollution scrubber, each of them moans a lot, 3 of them cheat, but everyone is $47000 richer in the end (except the cheaters who are $97000 richer until they get caught).