Most of them. One of them is going on a cross-country road-trip vacation with his dogs, another quit his job and bought a giant plot of land in the middle of nowhere to focus on gardening, another is finishing up her training to become an airline pilot (which reminds me I should give her a call - we haven't hung out since we got our private pilot's licenses together).

But the point being is that as people get older they have other things going on that keep them busy, even if they haven't chosen to start a family.

tl;dr: don't worry kids. I promise the next stage of your life (whatever you chose to do) will be as awesome to you as your current life