See, I disagree with the "should" imperative here. Why "should" anyone do something for the sake of the prosperous continuation of a specie? The notion that anything is owed to this nebulous idea of mankind is foreign to me. I'm concerned about the environment but not so much for the sake of humans - more for the sake of animals who have no conscious agency in preserving it, and are, by that token, innocent, so I can get behind saving it for them, but for humans? I don't feel the obligation to produce better humans, even if the hope of outnumbering idiots in the future was not already infinitesimally slim. Also, in raising kids you increase risks to your health, starting with added stress that no good parent can escape. I've no way of telling whether the accumulated stress of rearing a child - protecting it until it's old enough to fend for itself and then worrying for the rest of my life about them either way - will reduce my lifespan. Why should i allow that, that makes no sense? I'm sure my parents, too, wanted to believe that their sacrifices would result in a better life for their progeny - me - so where's the sense in me taking on the same stressors - or worse, given the world we live in today - and just doing the same thing they did, paying it forward ad infinitum? The outcome of that is the extension of a lineage and the specie, but to what end?
If I have a kid, it won't be out of some misguided sense of duty to mankind, or so that I can have company and care in my old age (which is the #1 worst reason I have heard so far - no child should be saddled with that sort of responsibility), it will be more "just because", with zero reflection on "mankind", zero expectations of them and for them, zero illusions or denial about what I'm undergoing (i.e., none of the "this is fine, I am fine" self-soothing bullshit), and with zero unsolicited & bullshit "wisdom" for would-be parents.
