Some cultures weigh the death of a child vs. the death of an old person in a way that makes the latter a much more severe loss, given the unique wisdom accumulated over years. I believe it is the opposite in developed countries today due to lower birth rate and the tendency to preserve inordinate amounts of information arguably making the wisdom of an old person seem mostly useless.

What's the word you call your younger self when you think you've got it figured out? Foolish seems too gentle a word. Before having my own, I would wonder why everyone spoke of losing a child as a pain beyond all others. I even had the audacity to think they were being dramatic - after all, they'd only known their child for such a short time. After having my own, I find myself breaking my own heart with the thought of loss almost like my spirit is trying to build calluses against a blow I pray never comes

I've not lost a child and I don't "intend" to, so for me there's the vast investment in bringing them in, raising them up, and to lose both the past and future at the "wrong time"...astronomically heartbreaking. Never used to cry during movies when a child is lost, now I do every time.

I think it's less loss of potential (though that is a good rationalization) and more that people who weren't sad when they thought about their kids dying didn't become ancestors to the current set of humans, via the obvious mechanism.

Your question just came off as incredibly obtuse.

That has what to do with this person saying a death is sad?