What if you have a child just to make yourself feel better and that kid goes on to have a shitty unhappy life wishing they'd never been born?
Sounds like a pretty shitty excuse in my ears, sorry.
Forcing a child to go through it all just to give your own life meaning? Totally selfish.
Using that as an argument for not having children is beyond silly.
Just say that you don't want children, it's ok, you don't have to make up reasons and try and convince others.
I think you're missing out on something amazing, but that's just my personal opinion.
Sounds like a pretty shitty excuse in my ears, sorry.