Examples where most people are worse off are easy to think of. I gave an example where everybody is worse off because it is an interesting scenario. I made no claim about how often that situation occurs. There is no reason for overall progress to grind to a halt — the Nash equilibria for a game can be arbitrarily bad. There is only the obvious conclusion that governments should get involved to fix these problems when they occur, including regulating lead use, given that we see plenty of governments that have not and have suffered the consequences.