Another point. In medicine, the best docs don't make the most money. Most docs now work for hospitals so the salaries are standard and they make your schedule and try to pack too many patient in. They actually treat you like an assembly worker and see you as replaceable.
When the majority of docs were in private practice, yes the better docs were busier and could make more money...but then you must decide how many patients can you see per hour and still give them excellent care. So, our financial ceiling is limited by quality of care! And reimbursement, of course. In private practice, If I was reimbursed $150 per patient, I could schedule 30 min visits for everyone. The fact is my average insurance reimbursement is $65 so I either see tons of patients, reduce my overhead, or just accept less salary.