This op-ed by David Brooks says that the largest proportion of the richest 1% of Americans are doctors. He says 16% of the wealthiest are doctors, compared with 8% being lawyers, for example. That's why health care costs are going through the roof, why Medicare is out of control, etc.
He doesn't break down the doctors' incomes, but it's pretty well known that the richest doctors are the specialists, the heart guys, the bone guys, etc. Many of them getting rich on Medicare because old people have heart attacks, broken hips, etc. The general practitioners, who keep people healthy, rather than repairing them after they are sick, don't make nearly as much.
It's a system where the rewards are misallocated, and that threatens to destroy the whole American economy.