I think I get it. The low cost is itself having a destructive effect. People, eventually, can't get the resource that is depleted. I just didn't register tha

I think I get it. The low cost is itself having a destructive effect. People, eventually, can't get the resource that is depleted. I just didn't register that as external, but it is if you consider the depleted future to be external to the wasteful present. An important point, actually, if I understand correctly. Thanks.