They are also earning 300k for first year analyst (it goes up more every year). 100 hours is pretty normal for what they are getting paid. Sustainable? Not for many but still a lot more of money for a 21 year old at the end of the day.
At least analysts can bail to the buy side and have a +EV path out.
London folks have it way worse too, I hear. Same jobs, 60% of comp, London isn't cheaper than NY.