This is a really bad comparison imo. The difficulty of sustainability and non-pollution is that it requires everyone to work together to not consume. If even a

This is a really bad comparison imo. The difficulty of sustainability and non-pollution is that it requires everyone to work together to not consume. If even a few parties decide to not cooperate they can consume everything that's left and the other people will lose out on their "share." In the case of an asteroid it's in everyone's interest to prepare as best as he/she can and cooperation actually helps. There's really no downside to preparing as much you as can.