I think it's simpler than that.

Us "numbers" people consistently fail to take basic human nature into account. Evidence of that, is everywhere; most obviously, in industrial/UX design.

Human nature is raw chaos. I have friends in the fashion industry, and that is an industry where human nature can cost (or make) a company millions of dollars. People that are good at understanding human nature, do well.

It doesn't respond well to number-crunching, though.

Also, as animal populations sometimes demonstrate, fertility can be a function of crowding. Pack a lot of critters together, and they tend to produce fewer new critters. Maybe the same thing happens to us.