If you want to make money, finance is really the way to go. There are many different types of jobs and it doesn't have to be on Wall Street. You don't have to go through med school or residency and the work is a lot easier. The income is easily in the 6 figures. Maybe it's a little more stressful because you always have to perform.
Many med students probably have the smarts, talent, and ego to do well in finance. They just don't know how.
I'd agree if money were the driving force for a student to go into medicine AND if it were true that most med students had the potential to do well in finance jobs.
I'm not sure if both of the above are true that often with med students, however.
My undergrad studies were in business at a top b-school, and I knew plenty of "I-bankers" who planned on taking the world by storm on Wall Street. They were likewise very smart, driven, hardworking students. So I don't think it's the case that ALL of the best and brightest students are going into medicine and should be going into finance instead because of the money. Those already going into the field are probably just as smart on average--though obviously in different fields.
But back to my original point... Yes, of course the promise of a secure, very good income recession or not is surely a motivating factor for many students to enter medicine. But I do think that most students in med schools ALSO do enjoy human interaction, studying science, working with their hands or at least with tangible items, or some combination of the above. You get very little of those in most finance jobs.
Also, I'm not sure that finance jobs are the best fit for most med students. My memory of most of the true finance gunners in b-school is that they often had very aggressive personalities, almost combative in the name of competition. Most weren't that concerned about working directly with people, most thought studying science was a waste of time--as was pretty much anything outside of the direct business of making money. And most that ended up getting some success were very risk-loving, always believing they had the biggest and best ideas.
On the contrary, I'd say most med students are risk-averse, preferring to take perhaps less potential pay but the more secure, guaranteed route. Many of my old Wall Street friends also lost their jobs post-9/11 when the market turned south. Medicine always has been and always will be one of the major recession-proof jobs that pays well.
And besides, for many physicians (specialists, surgeons, etc.), the income earned can be just a starting point to much greater wealth through wise financial investments. But again, this doesn't happen as often as it could because of some of the reasons I've listed above re: the nature of most med students. Smart and hard-working, but hardly the biggest risk takers in the world.