I have done community service several times, like helping at a grange and helping at a retirement home, you can help the community in ways that don’t or very rarely involve kids. You can help a friend with their kid without wanting kids and thinking they should not have had them, I’d also help them fix a car I don’t think they should’ve bought. With overpopulation and severe effects of climate change I would look down on having kids, because this current path isn’t sustainable, but that’s not the kid’s fault so we should still help the kid.

I think if you truly believe that, you should read about all the people who have spent months or years in total solitude and remained fulfilled. Having kids or not does not determine your long term happiness, many people with kids are unhappy even when the kids are grown up, because they didn’t learn how to be happy. I would expect being childless just gives you more time to learn about yourself, but that’s just speculation.