I find it really tough to harmonize the ideas that: 1) If you can't sell your labor to provide for yourself, you deserve to die. 2) You should have kids, and not only cost yourself $100,000 at least, and increase competition for resources.
The cynic in me thinks people want to see others fail so they can feel better about themselves, and more people competing for labor and capital decreasing the demand for labor will increase the number of people who society will deem unworthy of existence. By the odds, any random kid isn't going to change the world, they're just going to be another mouth to feed, and more than likely going to make things somewhat worse for everyone else. This is a blood-soaked all-against-all kill-and-die world, and what is a kid other than another knife pointed at you?
As far as I can tell, this seems about as rational as being proud to put out your own eyes with a red-hot grapefruit spoon.
As far as the "Kids give your life meaning" idea goes, giving one's parents meaning is a lot to put on a baby who can't even lift their own head, or anyone else for that matter. We're told all our lives that we're on our own, that anyone who needs anything from anyone else is weak and doesn't deserve existence (which is both morally wrong and incorrect). At the same time, it's supposedly okay to force a child to emotionally support you? That doesn't make any sense.
I can at least comprehend the racist argument, that it's one's responsibility to have kids to outcompete outsiders. I disagree with it for numerous reasons, but I can at least fit that idea in my head. Maybe that's a reason having kids squicks me out so much, is the only comprehensible argument to me I find repulsive and I've only heard it out of repulsive people.
Is the desire to have kids completely ruled by biological/hormonal factors, or a fear of ostracism for not "doing one's duty"? A lot of people I know and respect are good parents and don't regret having kids, but can't articulate why they did, so I'm not under the impression that parents are all cruel, broken assholes (though in my hometown there were numerous examples of this).
What is it about parenthood that isn't a curse on yourself and everyone else?