You've got confirmation bias. The people you read about were likely all great coders/writers before having kids, and their livelihood now depends somewhat on those activities. For the vast majority of us, githubbing and blogging are enjoyable but not necessary activities. When we have kids, yes there's not so many green boxes. If you haven't written books already, now is probably not the time you're going to start. That's not to say there's no free time, just not as much.