Wow... what a range...
A close family friend of ours hung his shingle back in '82. Solo private practice, no medispa, etc. One employee. Takes some insurance, I think. Always on call, for his own patients, stopped taking ER call after 20yr of practice... Does some cosmetic, some recon- mostly breast reductions and skin cancers, though. All in all, a small-time bread-and-butter plastics guy. He's happy, has time with his family, sent his kids to good schools, hours are decent. Makes about $250K- at least that's what's on the books. He refuses to do Botox, doesn't want to sell his own makeup line, doesn't put up billboards and TV ads, etc. Knows he could make more if he "marketed himself" differently, but wouldn't feel good about himself if he did.
I guess the bottom line is just that you have to strike a balance that makes you happy. And also- how much money do you really NEED? I mean, after 4/5/600K does it really make a difference? I guess if you want ten ferraris and stuff it does...