Indeed! And things would be similarly dire if everyone indulged their privilege to have ten children.

The reality, though, is that neither is the case. And because neither is the case, we can have a thoughtful discussion about human populations.

In particular, given the immense impact humans are having on the world's ecosystem and the extreme rapidity with which we're extracting supplies of resources from the accessible locations within the earth's crust, we either have to accept a much lower-consumption model of living on average (let alone raising everyone to affluent-Western level), or we have to accept a much lower population.

Either way, the current growth-based socio-economic model is toast.

Since the model is toast regardless, all the reasoning you give about depopulation has to be viewed skeptically. This does not mean, however, that we do not owe parents a tremendous debt of gratitude: it is utterly necessary for the continuation of society and of our species; and it is very demanding work (even if it is often rewarding). We don't in other areas withhold our gratitude from those who love, say, running a soup kitchen, or being a nurse practitioner. Neither should we for parents.

And, yes, as a society, it does seem that we put too little importance on the next generation and too much on ourselves.

But it doesn't mean that not having kids is anti-social. Indeed, in case of grave threat, sacrifice of life or reproductive capacity is one of the most pro-social things one can do. Resource limitations are a grave threat. So neither should we scorn people who make that choice, especially if it is in awareness of the difficulties our children will face in fitting into a planet with too much carbon in the atmosphere, too much plastic in the ocean, too few rainforests, too much water used for agriculture, too much topsoil runoff, too little easily accessible copper, and so forth and so on.

Not having children is okay. We're good. We're good for a long time (unless birth rates drop far more). Well, unless we are idiots with economic policy and we can't figure out how to run a non-growth-based society. But, again, in that case we're doomed either way.

However, doing your own conspicuously consumptive thing while not supporting or, even worse, scorning (responsible) parents is unconscionable.

We need to have somewhat fewer people on the planet. But we need every generation, and we need every generation to be wise and kind and well-educated, and the first and most important individuals in making this happen are the parents.