I'll clarify.....if you are physically & mentally able to have a child, but simply choose not to for selfish reasons, I personally think you are making a huge mistake.
I say this from experience. I had no interest in kids for the first 37 years of my life, including 10 years of marriage. I didn't see the upside. There wasn't a bigger selfish prikk than myself.
For me, at least, it has been the only true joy I have ever known. Not saying its never a pain in the ass, expensive, and frustrating. It is! But, at the end of the day, its absolutely what lifes all about.