There are a few weird and irrational biases I see going on amongst techies who frequent HN. I'll just talk about one of them because bias is a tough topic to talk rationally about.
The one I want to discuss that I see a lot of hackers doing is creating a need to do everything themselves. This leads directly to the delusion that side projects are things to take Really Seriously.
Sure, if I wanted to, I could chunk out all the work it takes to build a product, take it to the market, refine it, then finally build a company around it to take the load off.
But unless you're a real honest-to-god genius, then you're going to make mistakes, and those mistakes can add months, or even years to the time when you can Call It Done and go back to spending the time with your wife and kids.
If you're not absolutely strict about not letting it override your personal life, you will end up sacrificing your life to the jealous God of the Market.
You might try to respond by moving the goalposts, saying that the real goal here is learning, not achieving some kind of outcome. But do I really need to ship a product to learn?
There is a class of activity that is actively distrustful of the market, which insists that all learning comes from the creator's own mind. It's called art. If Picasso thought that the market was worth listening to, then we wouldn't know his name today. Artists by their nature listen to other artists, and not you. That's what makes it art.
Side projects should be considered to be more art than business. Art doesn't fuck with your personal life. Art informs your personal life. Whether you're creating it or enjoying it. If I'm sitting there hacking out a weird new concept for accessing databases and my wife comes into the room and wants to talk about our son's baseball game, I put down the text editor and listen to my wife. I do not tell her that I'm currently in flow right now and jeez could you really just come back later after I'm taking care of this Really Important Thing.
If you're bleeding your professional life so far into your personal life that you are even for a moment taking it more seriously than your wife and kids, you have fucked up your priorities. I would never ever ever even dream of doing this. Everything else is noise compared to my personal life.