Yea, my comment was looking at it from a global point of view. We simply can't base the global economy on an infinitely growing population--it's ultimately a ponzi scheme.
Many countries don't have a Social Security equivalent, and people rely on their families instead. So not having kids can mean not having anyone to take care of you in old age, but it's maybe still ok if your siblings had kids. It's not that the economy overall relies on that.
