You’re speaking with authority but have no sources. What can you point me to that says working for longer than a month at 72 hrs/wk is unsustainable? Sure everything you say can happen. But also you can feel invigorated and it can be extremely healthy to feel like you have a purpose. It’s up to the person who is signing up to work to decide. And guess what? Nobody is forcing you to work 72 hrs/wk. There are plenty of other jobs out there.