They call it the Nobel disease. Linus Pauling is the prototypical example. A brilliant chemist who won two Nobel Prizes, one for chemistry and the Nobel Peace Prize, in his later years Pauling became convinced that high dose vitamin C was a highly effective treatment for cancer and the common cold and, expanding upon that, came to believe in the quackery that is orthomolecular medicine. As a result, Pauling's reputation was tainted for all time, and he became known more for his crankery than his successes. Read the story here.
Respectful Insolence: The Nobel disease strikes again
Whenever you see an 'investigator' charge patients to undergo an experimental protocol, be very very wary.