I don't understand why people, generally on both sides of the issue, just ignore the social effects of it and instead just focus on the personal. I suspect most don't intuit how rapidly fertility shifts population sizes, because it's an exponential. A fertility rate of 1 means each generation decreases by more than 50%, compounding. So after just 5 generations and your generational size is down 97% with your population doing the exact same, staggered out by a few decades.

And fertility determines not only the size of a population, but even the age ratios within that population. Low fertility means you end up with far more elderly than you do working age. Far from this vision of being a society with more for everybody, we'll be creating societies where labor is ever-more scarce, economies are primarily dedicated to helping sustain the elderly and simultaneously collapsing at the same time. It's not going to be pretty.

For these reasons, and many others, I think the social aspect is one of the most important. Self fulfillment and these other things are very important and good, but if we don't have children then we're going to be creating some pretty messed up societies for our descendants. We're likely going to get to see this play out in South Korea during our lifetimes. And I do wonder what their descendants will think of the South Koreans of today.