I have been cutting hair since I was 14 and many times matched my salary as a barracks barber in the Marine Corps, problem is the inconsistency. Most men want their hair cut fresh for the weekend, means Fridays and early Saturdays. Of that 60 he can max out in an hour, you have to account for chair rental (if you don't own the shop) or utilities if you do, plus taxes, supplies, maintenance, etc. It is a very viable profession, especially if you have a good core of customers, just inconstant and I value stability.
The best part is the social aspect of the whole thing which is why I'll retire at 57 as soon as I am eligible and work in a shop for spare cash flow, lol.