Is it? Or is he a monster who brought 5 beings into a existence of suffering?

https://www.samharris.org/podcast/item/is-life-actually-wort...

The worst thing you can do for the environment isn't flying; it is having a child. Having multiple, is, well.. X times worse.

Our population isn't declining either, as long as you watch it from Earth's PoV instead of whatever nation you're from.

I don't want to judge a specific person on having a number of children, and being the parent of one child I can't even fathom having five (!!!) but the general notions you made in conclusion to that I disagree with.

Is it best for society, though? The earth is already massively overpopulated. Perhaps it's best if some populations decline. And is it the best for himself if, for instance, the kids grow up to hate OP because of, say, global warming forcing them to fight to survive? Or if he has to live to see them struggle with that?