Two. Exactly two. Including you.

The other person just had a fundamentally negative, defeatist and apocaliptic perspective on the world. And while such an attitude doesn't necessarily tell whether they're sane or insane, it does show they're not the right person to discuss with about the issues of the sustenance and advancement of the society.

And you. You not only said selfishness isn't wrong (you've just lost moral high ground) but also said you dont give a fuck about sustaining our society (with the childbirth comment). With these two statements, you've shown conclusive proof that you're not qualified to discuss about what's right and wrong, and what's good or bad for the society. So you're ruled out as well. Now that I think about it, you do sound insane although I didn't mean that in my first comment.