You are part of the hyperactive onsite mainstream HN crowd.single or married but no other responsibilities (children, aging parents and other such commitments). When you live the other life you will see how work just fills up and an extra day feels like a miracle.
Exactly this. Once you have other responsibilities or hobbies outside of work, a 12-hour workday will leave you with absolutely no free time. Add in your typical bay area commute time, and you'd hardly have time to sleep.