People are very conscious that a child costs a lot to raise and the reality is usually worse than their estimates. They know children will impact their career and promotion opportunities, so a lower expected income just when they need it more. They know they no longer live next to their parents so the support structure they have in place is flimsy.

You make a philosophical point while the reality is already clear enough. Everyone has a friend with kids so they hear the stories. The “scary” ones stick longer than the nice ones because it’s easier to understand financial woes, health issues, and problems of this kind.