Each one of us was harmed by being brought into existence. That harm is not negligible, because the quality of even the best lives is very bad—and considerably worse than most people recognize it to be. Although it is obviously too late to prevent our own existence, it is not too late to prevent the existence of future possible people.
David Benatar (2008). “Better Never to Have Been: The Harm of Coming Into Existence”, p.7, Oxford University Press