Many other cultures (and even many of my relatives) frame the task of rearing children as means to better ensure for your own care towards the end of your life, rather than as a high-risk endeavor comparable to purchasing real estate.
I've heard of this, but what kids actually stick around to take care of their parents when they're old? In fact, isn't that rather cruel? By the time the parents are unable to take care of themselves (if they get to that state; lots of elderly people are fully mobile and capable of taking care of themselves), their kids will now have their own kids, and it will be flatly impossible for them to both have two jobs, take care of their kids, and take care of their parents all at the same time. That's an unreasonable expectation to have of your children.
Apparently this is the case in Singapore, which relies on family support instead of welfare. Retired parents can even sue their children if they fail to adequately support them, according to this Economist article: