If there is nothing and from this nothing we bring forth a being into this world, regardless of whether it suffers or not, we have made the being without its consent. Therefore, if this being later in life comes to the realization that they do not like existence and would prefer never to have been born, then they would have benefited if we had never brought them into existence, even if we could not know that unless we already bring them into existence.
Moreover, even if the being we create enjoys existence, before we create it it has no wants or needs — including to exist. So even then we simply force it to exist and then gamble that their existence is good enough — or delusional enough — that they are satisfied with it. But even such a being, had we decided never to bring it into existence, would have lost nothing by it because unlike the suffering being that already exists and regrets its existence, this one, being non-existent, has neither wishes or needs.
So life is a terrible gamble in that sense and a totally unnecessary one.
In truth, I’ve yet to see a good argument against anti-natalism. All I’ve seen is a bunch of mental gymnastics born from cowardice.
Perhaps that is because there aren’t any good arguments against it.