Because you bring them into the world in the knowledge that their lives will be somewhere between slighty worse and a lot worse than yours. I don't plan to hav

Because you bring them into the world in the knowledge that their lives will be somewhere between slighty worse and a lot worse than yours. I don't plan to have children anyway, but I've concluded for instance but there's no point in making sacrifices today in the service of enjoying a comfortable retirement, because by that point western society will no longer be any fit state to provide for a conventional "life of leisure" retirement.