Ask HN: Is success impossible for a part-time startup?

I've got a (software) idea that I want to turn into a startup. I'm not motivated by money past a certain point. I want only to create a stable business around my idea and keep my face and family fed. My real motivation for starting a company would be that as my own boss, I would be able to set for myself a low-hour (>20, <40) work week. This is mostly in reaction to my current situation, where I am employed with an acceptable salary, but quite unhappy with the number of unpaid overtime hours I end up sacrificing to my employer. I would gladly forego a pay raise for more time off. However, every article I've come across that highlights startup companies and some of PG's writings on the subject have dashed my hopes. All have one thing in common: "insane" hours. They are telling me that I shouldn't bother taking the risk. My take-away is that in order to have any chance of a startup not doomed to failure, you have to be 1. young 2. unmarried 3. able to fall back on your parents and 4. willing to make your company your whole life. Some people I have discussed this with claim that this is due to CEOs being "in love" with their idea and doing everything they can to make it succeed. The implication for me is that I don't care as much. The only thing I have to offer here is that I do in fact have a lot emotionally invested in this, however the only thing I care about more is being involved with my family, and I'm tired of sacrificing that for financial gain. I'm sure that startup CEOs who meet the criteria have a distinct advantage in a competitive market, and are more likely to become wealthy. However the idea that failure is guaranteed for the less insane seems counterintuitive to me for a number of reasons: 1. This idea has been knocking around in my head for years with no implementors, so why rush now? 2. I believe strongly in the importance of exercise and rest to one's ability to perform. I blame most of my failures or missed deadlines on the all-nighters and skipped exercise that I did in an attempt to meet those very same deadlines. I think a short work week should allow me to demand that I and my employees are rested and healthy for the 4- to 6-hour blast. 3. I have seen and have been guilty myself in the past of not using time efficiently during a >8-hour daily grind. I think that with a set 4-6 hours to get all my work done followed by lots of free time, I and employees would easily stay intensely focused and driven during that schedule. I know the argument for context-switching and time spent "getting in the zone" but I believe that this is negligible compared to zoning out due to lack of sleep/lack of exercise/burnout/etc. 4. Work weeks are shorter in some other countries (France). Can't it be successful in the U.S.? 5. Google has their 20% rule. I think I should be able to work at least 20% less for the same or better productivity, if that 20% is spent on recharging activities like time with the family, etc. 6. Some startups spend 80 hours per week per employee and still fail. This makes me suspect that if the idea isn't good enough to succeed on 20 hours a week, it might not be good enough to succeed on 80 either. I'd like to hear your comments, but most of all I'm looking for a counterexample: a pointer to a single (startup) business that is profitable--not necessarily booming--with short work weeks.