I agree with you on the latter point, but I want to also point something out on the former. Many people who are of no "proper" means to do so continue to have children. And they make it work, even if it may be uncomfortable and require sacrifice. So the issue is not one of finances, but priorities. Winning an IPO lottery being the baseline where you feel comfortable for having children doesn't mean that such is the inherent baseline, but that you simply prioritize comfort and wealth over raising a family. And that is okay.

This nuance is important; it emphasizes the real issue is not economics, but culture! We've created a society that values the pursuit of wealth and comfort more than family, and it's likely this system is not sustainable. Not everybody can be wealthy, because wealth is relative and mediated by what exists. If 30% of people want something and there's only enough for 3%, then it doesn't matter what the relative wealth is among these people: 90% of people won't be able to "afford" it, and that will never change. A post-scarcity society will never exist alongside consumerism; we'll simply take what we can have for granted and lust over the new scarcities.