Still, regardless of the eye-watering amount of money, there's still a maximum amount of useful work you can get out of someone. Demand too much, and you actually lower their total productivity.

(For me, I found the limit was somewhere around 70 hrs/week - beyond that, the mistakes I made negated any progress I made. This also left me pretty burnt out after about a year, so the sustainable long-term hourly work rate is lower)