You can make lots of money working 30-35 hour weeks. Perhaps those working 60 hours a week just aren’t as clever, or haven’t found a valuable enough niche.
Like, could I make the same money for half the time if I e.g. started my own gig? Maybe. But maybe is not good enough, and with a spouse, kids and a mortgage, I can't afford to test it - it would put my family at too big of a risk.