The ultimate answer to this is that, in our society as it presently exists, those who don't have children will spend on average 20 or so years of their life freeloading on the children of those who did.
So my two kids will financially have to pay not only for the support of not only my wife and I but also for that of one or more people who chose not to have children. With all the cost of time and money that entails.
I loved the term “parentsites” in the article.