Is that really true? Doctors are most of the best-paying jobs in the US [0] It seems to me that if you're bright, and care about making a lot of money, medicine is absolutely the way to go. Yes, there are some people who strike it rich with startups or high finance, but that's essentially buying a lotto ticket.
[0]: http://www.bls.gov/oes/current/oes_nat.htm#00-0000 (sort by annual mean wage, Anesthesiologists, Surgeons, Oral and Maxillofacial Surgeons, etc.)