Lots of reasons. Overpopulation, I'd feel really guilty for bringing another person into this world. Loss of species saddens me greatly and humans are a huge factor in this. Nappies in landfill (yes I know about cloth). Competition for jobs. Bullying at school and in work. Childbirth. I watched the birth video of a Youtuber I follow recently and she had no pain relief and screamed like she was possessed. But I imagine what comes after you birth the baby would be even more difficult, at least for me. I just don't think I could cope and I wouldn't want to risk it. I've had depression and anxiety most of my life (mostly better now but still) and think a screaming baby would push me over the edge.
For years my mother and friend would try to convince me otherwise. My friend would laugh and say of course I could look after a child, not to be silly when I told her I could barely look after myself. But she'd told me herself how difficult it was, how she'd be crying on the phone to her mother due to the sleep deprivation. I couldn't handle that.
Occasionally when I see friends cuddling their kids I feel a pang of I'm not sure what? Sadness that I won't experience that? Or something. I had a mostly happy childhood with a good family and I guess I thought I'd do the same and have my own at one point. But then I realised that they're not for me. If I had lots of money, better mental health and the world wasn't in such a state perhaps things would be different. I like to think perhaps there is another me on a parallel universe with a couple of sprogs haha. But I don't think I could handle the reality of bringing up a child.
I also wonder how people get the time for other things? Like work? I'm stretched out right now and don't know how parents cope in the workplace. I can barely get myself up and ready in the morning and when you have kids you need to organise someone to look after them if you're not around. I'm scatter brained and would probably forget to arrange childcare. And I'd feel terribly if I couldn't look after them properly, provide for them and keep them relatively happy.
My DB has 3 young kids and they're a handful. I'm amazed one of them hasn't been seriously hurt because they're allowed out to play in the street unsupervised and don't have any road sense from what I've seen. I enjoy spending time with them to an extent, they're cute and funny but can also be quite trying and naughty at times. And they have So.Much.Plastic.Crap. Every time a birthday or Christmas rolls around more plastic crap is added to what is already there. I think of it all ending up in landfill and how many children there are with plastic crap and it makes my head spin.
Kids can adversely affect relationships too. A friend of mine had a planned for baby and her DP basically had a personality transplant overnight. He just couldn't cope and took it out on her and they eventually split.
Then there's the fact that you could have a kid with a disability or something could happen to them. I couldn't cope with that kind of thing. A friend of mine finally had her dreamed-for baby and the child has a life-limiting condition. Also she's in the US and constantly getting hit with medical bills. It must be so bloody hard.
I'm not very good with kids. I mean I can try but I'm not a natural. And they can be very noisy and irritating at times. The shrieking and random crying at nothing. Very expensive to look after. I think I'd find it very stressful and like others have said, you can't give them back. And then there's the being judged for doing/not doing certain things.
I like to travel and enjoy a quiet home life. I love animals. I like doing spontaneous stuff. I like lying in and not having to worry about looking after someone else. And I'd hate to mess someone up because I couldn't provide for them. So it's just me, DP and hopefully a rescue pet or two in the future. I enjoy my life and wouldn't want to risk messing up a child and myself.