"It certainly cant be the money Wall Street is the faster and more reliable route to wealth, as evidenced by the skyrocketing of applications to M.B.A. programs."
Why cant it be the money? The earnings of an MD are not that bad. The stress levels are much lower than Wall Street. Plus there is greater job security. If you compare the US to Europe, where physician salaries are much lower, students are not thronging to medical schools like the US. In fact, a major reason for our health care woes is the high salaries enjoyed by physicians which subsequently leads to higher insurance costs.