Not being in that field, I can only speculate. I would imagine its the joy of helping people feel better about themselves because you make them look better. People often say looks don't matter, but that doesn't mean people don't feel bad when they don't look like models, so being one step closer is a confidence/ego/self esteem booster.
I would think that is the best non-monetary reward for the hairdressers and beauticians out there. I'm more than happy to be wrong though, as I said, I am not in that field.
You're certainly joking when you say money aren't you? As an ex hairdresser, I can only say that it ranks right down with waiting tables - at least, to begin with anyhow. It's good to get a mop in and send it out looking like a million pounds though and I would imagine the beauty racket is much the same.
I am not a hairdresser, but I can tell you that my hairdresser is fantastic and greatly appreciated by all of her very loyal clients. She has never had a work shortage, even in this down economy. She is booked and I have never missed an appointment in the 6 years I've worked with her.