How is intentionally choosing to not have children a sacrifice if you live in a western country? We're at a point where these countries need more people, not less, to have children. Having and raising a child is a difficult thing to do
There are many people who really, truly want children, who would be sad not to have them, but feel it is morally questionable-to-wrong (rightly or wrongly) to bring more people into what they view as a failing world. That is a sacrifice, whether you perceive it as such. It is people making an eventually irreversible decision to not live the life they want to live.
And I disagree with the idea that we need people. The capitalistic society we built needs more people, the planet most certainly does not. I do not think the needs of humanity are de facto more important than the health of the global ecosystem.
