raising a child is also work to be valued (which you benefitted from yourself, btw).

This.

And it’s not a binary thing, it’s a scale. Kids who are supported by emotionally stable parents who are able to spend their time together are more likely to succeed in life than kids who are left to their own devices and end up picking up all sorts of insecurities due to the parent being sort of a nerve wreck, and them eventually feeling like a burden all the time.

I will happily support my colleague spending more of his time with his daughters, because then when I’m old, I have higher chance that those daughters being confident, nice and educated adult people who can produce economical value. Only then, part of that value can come back to me in various forms of support, whether it’s pension, better social services or just more options. (Unless they move to another country – but then again, that depends on the relative quality of life in this country, which in turn boils down to the same principle.)

Now, maybe I’m a nice guy here, but none of the above logic requires me to be nice. I could be a totally selfish asshole and still the position works out the same.