Some issues:
You haven't accounted for taxes.
Utilities is far too low.
Rent may be too low--if you're averaging 1.5 customers per hour, then you're in a relatively accessible area with decent traffic and if you've got 2-3 rooms, you're likely renting at least 1000 sq ft. In all likelihood, you've gotta bump that $2500 of rent up to $3500.
There will be professional services (lawyers, accountants) fees (~$300-$500 -- I'm not in the industry, but hard to imagine there aren't a number of legal issues that arise over the course of a year that would average to $500 / month)
'Overhead' seems low. $500 is $125 / week. Cleaning supplies, maintenance, paying for maintenance/clean-up services/laundry services, etc. is likely closer to $1000.
Insurance is likely running to $1000.
'Miscellaneous' business risk (higher chance of violence, theft, and attracting unsavory characters -- all of which costs money somehow) probably runs at least $1000 per month on average.
After including the above, you're probably running at ~$12,500 in profit before taxes. After tax, that's alright. It's not enough for someone to be doing really well with and, considering all of the risks, it's not great. No one's getting rich on that for sure.