Two things:
1) For the OP and the replies, it would be more realistic to say "average income for someone with a graduate degree."
2) Second, the career paths outside of medicine are very different. Almost every other career is pyramidal: For every lawyer making $1M as a partner in a "white shoe" law firm, there are 100 scrambling up trying to reach that status. And if you have one bad year with billing, you are gone. The same thing with engineering, management, finance, etc., you are in competition for the top money every hour of the year. One or two slip-ups, and you are off the pyramid. And the things physicians are best at correlate very poorly with the big incomes in other professions. The brilliant engineer is buried in the organization at Boeing while the socially-savvy smooth-talker climbs the corporate ranks to the big salaries. A lot of physicians like to think that they would be at the top of the corporate world. Nope. (Just look around at how well physicians handle health care.)
On the other hand, if you are admitted to an American Medical School you are basically set. Yes, there is some attrition, and, yes, there is competition for residency spots, but once you graduate you are basically guaranteed a significant fraction of the salary of 30 year veteran physicians. Once you graduate residency, unless you are in a competitive elective specialty like plastic surgery, you can to some extent relax. In medicine, the best EM physician at a hospital gets paid basically the same as the 15th best. Competition with your peers is basically over. Again, compared with most other lucrative professions where every day of your career is a fist-fight.
The world outside of medicine is not as cushy as we often think.