> I heard Elon does 120 hours a week. /s

It's not exactly hard at his level. He can delegate absolutely everything and cannot be obliged to do anything. He can pick who is around him at all times, and they are usually obligated to cater to his wishes. 120 hours of casual chats, meetings, presentations, shared meals, and travel count as long as it's related to any of his 3 major businesses.

I once worked real 60-70h weeks, ca 4 weeks nonstop in order to meet a critical deadline. Probably took three days off in that timeframe. I basically slouched in the living room all day and hacked away, surviving on chocolate and nootropics. Can’t recommend this, at all! My body tenses whenever I think about that, three years later, and I never wanna do that again.

I've seen tons of people doing it for extended periods of time. I can think of - ambitious people working in competitive environments (research, corporations, students) - doctors/dentists/nurses, lot of them work long hours and their job require focus - small business owners

Medical residents work 80 hours a week. And that's an average over 4 weeks, so they could work 90 easily one week.

40 is nothing...

Lawyers and bankers regularly do 4000 hour years. Doctors often average 60 hour weeks for extended periods of time. What are you talking about?