I won’t lie to you, there were some truly 100 hour weeks, but for the most part I worked precisely 96 hours per week in the PhD program and I loved it.

6 days of 16 hour days. It was fantastic. I had 3 labs and used parts of 4 others across 4 buildings, ran my main research and several skunkworks side projects, and optimized every moment I could. 3 years of that (with a week here or there for a holiday)

I was happy.

When we are pursuing something we are passionate about, when we are completely immersed in that thing, it is the greatest tribute to being alive.

I either was reading research papers or walking between buildings while eating, I automated some reactions and characterization so that I could read research papers while at the gym, and did numerous other things that made a 3 person project no problem for one person.

But to come off that high is hard. Everything seems slower when I’m not in that groove. I get bursts of it, but really being in that flow is such a joyous thing.

I hope those working on the module for those crazy hours were doing so because they were passionate about it. If not, then you are right to ask “what kind of life is that?”

Dedicating one's life to one's work (including long hours) can be very high quality: if you have an active interest in what you do, pride in what you produce, and you see yourself as not just doing some task that some employeer/customer told you to do, but you see your work and its output as symbolic of your own personal standards, then the rewards are more than sufficient payoff for the time spent. And the time spent itself can be quite pleasurable, too, even if time spent is very high.

Of course, if you've not managed to find something in life that both makes you feel that way and allows you sustenance, you're probably going to ask the very question you did. Human experience is simply more broad than that.