1. Not everyone needs to reproduce. We're over populated anyway.
2. I don't particularly even like kids nor censoring my language, discussions or activities due to the presence of rugrats. (Though I do act friendly and proper with kids of friends. Just glad they ain't mine.)
3. They're a full time commitment and some of us have other priorities with how we spend our time, money and energy during this very brief lifespan.
4. I could care less about societal expectations. checking it off some bulleted list because "you should accomplish such and such by such and such and such age to be seen as successful." Wife and children, fancy house in the burbs, white picket fences, SUV, practically LIVING at work to keep it all up, etc.That crap means nothing to me.
5. There are other ways to leave your mark upon the world after you're gone. How many people recall if Shakespeare even HAD rugrats?
6. The world is pretty sh** right now, also. Not a super environment to raise them in.