Childless people don't feel bad for parents for the same reason they don't feel bad for startup founders that work 100 hour weeks. You're putting in the effort for 95% your own benefit (a child that grows up and keeps you company on Christmas in old age, or a big pay day from selling your company), and 5% societal benefit (children growing up and joining the workforce, or a company providing a valuable service and employment). At the end of the day, there will be enough people that pursue these things without any extra incentives so you don't get the pity as well. You can disagree and still see the argument as valid. I certainly won't give a shit if no one pities me for being a parent because the time and effort is mostly for me -- just like it is for everyone else.