It's better for them individually, and under the current conditions. That doesn't mean that changing the conditions (e.g. by some measure that reduces populatio

It's better for them individually, and under the current conditions. That doesn't mean that changing the conditions (e.g. by some measure that reduces population of the largest cities) cannot bring a situation where the average person ends up better. In ML terms, the local gradient may be leading you to a local optimum. By the way, individual people aren't good at all at evaluating invisible, long-term costs like that of pollution and its health risks.