Are child-free people selfish?
The answer is no, of course not. But let me elaborate a bit…
When you purposefully opt out of parenting, people sometimes assume it is because you just don’t give a crap about anything but yourself. They figure you’d rather spend your time in a hedonistic frenzy of consumerism and self-absorption, frolicking around in a never-never land of no responsibilities and complete freedom rather than contributing to the molding and shaping of the next generation.
That’s not being selfish; it’s being smart. 
But all joking aside, being a parent is a tough job. It is perhaps the toughest job that one could ever undertake. It has risks and rewards just like anything else. But having children does not automatically qualify you for a “hero” award, nor does it mean you are a better person. It simply means you have chosen to become a parent. Not all parents are credits to humanity, nor are all children.
Many teachers, social workers, community volunteers, youth group coordinators, athletic coaches, art instructors, politicians, and people from every walk of life have chosen to remain child-free while making huge contributions to their communities and fellow-man. All of them are helping to pave the way for the future generations, and many will have a lasting influence and effect on the lives they touch.
Do we discount their contributions because they did not raise children of their own? Of course not.
It is also wrong to assume child-free people do not like kids, or are damaged from bad childhoods. Many have simply evaluated the decision and concluded that for whatever reason, parenting is just not an option they wish to choose for themselves. In this day and age, having kids is not a social obligation; it is a lifestyle choice.
We are all selfish to some degree, in the interests of ego and self-preservation. But if the reasons for deciding not to have kids are to be viewed as selfish, so too must the reasons for deciding to be a parent. After all, there aren’t many people who can answer the question “why did you have kids” without starting with “because I wanted…”
At the end of the day, we are all just trying to make the best choices for ourselves. The important thing is to make the best of it, whatever choices we’ve made.