Well, the fact is that outside of most places and people you're much more likely to spawn babies than get/infect with HIV. But point taken.
I just mean that when you're young you don't want to have kids because you think there's plenty of time in your life and you want to do other stuff; whereas when you're older you realise there's no time at all, and you had better get doing the other stuff right now. In many respects it's a lot like finding time to have dentistry. You can well believe that the dentitsry is a good thing, but it's expensive, time-consuming, hard to fit into a schedule, and painful.