My personal experience working full-time and working on side projects over several years in my early twenties has led me to a relatively pessimistic take on the idea, at least from the perspective of realistically building something serious and taking it to market. It wasn't until I actually quit (more precisely, got fired) and went out on my own that I was able to produce anything non-trivial, although I'm entirely bootstrapped and never took any investment.<p>Some of it might just be that I had demanding jobs. It's true that the network service provider arena is particularly 24/7. However, I went through half a dozen jobs between 18 and 22, and some afforded me plenty of free time outside the 9-5. With the easy jobs, I was demoralised, frustrated and/or bored, which didn't lead to a lot of spiritual energy for pursuing side projects diligently. With the more intense jobs, I was so busy that I had to try to squeeze in my side projects in the after-10 PM bracket. This all presumed no social life to speak of, by the way; the moment life even vaguely threatened social engagements, it was all out the window. Worse yet, staying up till 5 AM working on my side projects and trying to make it in at 9 AM for my actual job wasn't sustainable. It was arguably the immediate reason that led to my firing from the last job I actually had. It's not just a time thing, of course; sitting in an office all day is draining, even if one's job isn't very demanding. Even with my bright-eyed, bushy-tailed energy at 20, I often came home exhausted and would often spend my side project time just looking at the screen without getting much done. And, as I said, this is _without_ factoring in any other concerns whatsoever -- social life, personal life, working out, errands, grocery shopping, etc.<p>Anyway, maybe some people can do it, but in my view, this is no way to build something serious. I didn't start really making progress until I could afford to go "all in" with my time and energy. Also, it's important to remember that one is competing with folks who _do_ have the luxury of working on their venture on a full time-ish basis. That's quadruply important if go-to-market time is a serious linchpin of the venture.<p>Of course, the problem of bootstrapping while having a relatively high personal expense base is that the inevitable consulting required to support it sucks up all of one's time in the same way the day job used to (but with much higher economic stress and cash flow volatility), so it's not that going into business for myself opened up unparalleled opportunities to build product, either. However, even so, it beat grinding myself to powder.<p>EDIT: In one of my less intense jobs, I tried the approach of crashing out as soon as I came home (e.g. 7 PM) and waking up at 2 AM to spend my "best hours" on development. The actual day job could have the sloppy seconds; it wasn't a development job and didn't ask much of me. That was all good and fine, as long as one is comfortable with exactly two modes of existence: sleeping or sitting at a computer.