Quote from heech:
One thing that's really scary about medicine... if you piss off the wrong people in residency, they can destroy you. They can end your career, and essentially end your life. Residency directors + attendings have the complete, total authority to permanently make you unemployable as a physician, while you still have your $250k in debt to deal with.
As far as medical innovation/advancements... I used to (and still dabble) work as an angel investor. I've invested in quite a few medical technology companies. It's a long, long painful process. Brilliant technologies often shrivel up and die because you can't get billions in capital, over many years, to get it through the regulatory process. And even then, it can still fail because 60 year old physicians are too stubborn (and rich) to change the way they work. (Look at the slow uptake on EMR, for example.)
Everything, abosolutely everythig except two things you have written, applies to some other fields as well: Phd. molecular biology, physics, chemistry, biochemistry, chemical physics, theoretical mathematics, and perhaps a few other fields.
The two things that don't apply are: 1) if you are working on a Ph.D. in the hard sciences or theoretical mathematics, you don't pay to go to school, you get paid; 2) when you graduate, if you do, and after you do a post-doc for several years, you make less money. You work just as hard, if not harder, than a physician, and you have to use far more brain power, but you get paid less. But the work is fascinating and you don't have to poke a light pipe up anyone's rear end..
There is a reason these are called the "hard sciences"-- not to include theoretical math, which is the most intellectually challenging of all, but not a science.
Medicine, as it is routinely practiced, is mostly a trade. The reason physicians can make so much money in this trade is two-fold: 1) medicine in the U.S. is a cartel where access is strictly controlled, as is the production of new M.D.'s, and 2) you are offering a service that can't be refused.
These latter two things are not true of the "hard sciences".