I would love to have a child but don't feel it would be fair (on the child) to be brought into existence as they would have no other family (I am an only child - they would have no aunties, uncles, cousins etc). I would be an older parent too, so greater risk of the child losing me young, or bring born with disabilities.
Does this make me selfish? I am surely putting my hypothetical child first. I want them, but I think there is a good chance their life wouldn't be so great, so I am opting to spare them from it, even though it brings me extreme sadness.
I can't therefore contribute to the next generation. Do I feel bad about it? Yes, I do. Do I worry that nobody will care about me in my old age - yes, all the time. I often walk around looking at parents with young children and feel like an absolute failure. I have gone so far as to have contemplated suicide over it.
But the one thing that does bring me hope and a sense of purpose for the future is the idea that I can get involved with other things which are important for society in the form of voluntary and charity work. I won't be looking after grandchildren when I am older, but I hope I will be contributing in other ways. And maybe (selfishly) building up connections and a network of people who will look out for me when I need help too.
I feel that's all I can do.