How can someone so intelligent be so, don't want to say stupid as that sounds harsh!
The answer is more complex than one would think. I read a good and detailed analysis some time ago, but I can't locate it right now. But here is the gist of it:
INDIVIDUAL REASONS:
1) Some decide to give it a try, and believe his/her personal experience is adequate to decide if it has worked or not. Various judgmental biases and errors have a strong tendency to make even the most worthless interventions seem valid.
2) Some choose altmed out of a broader philosophical commitment. Their cosmological outlook differs substantially from the rationalist-empiricist worldview that underlies scientific biomedicine. They disagree not only about the basic constituents of the universe and the nature of the forces that govern them, but also about what are valid methods for settling the issue.
CULTURAL FACTORS:
1) Low level of scientific literacy – It is possible to go through school with very little exposure to science. Some years ago a Canadian survey found that only 52% knew how long it takes the earth to orbit the sun. Consequently, most people lack the basic knowledge and critical thinking skills to make an informed choice when they must decide whether a highly touted health care product is a sensible buy or not. When consumers haven't the foggiest idea how bacteria, viruses, prions, oncogenes, carcinogens,etc. works in the body, various types of alt med seem no more magical than the latest breakthrough from conventional medicine.
2) An increase in anti-intellectualism and antiscientific attitudes. Just take a look around this board, and you will see the point.
3) Clever marketing of extravagant claims by the alt med community. Routinely, promises are made that no ethical scientifically trained practitioner could or would make. In addition, new diseases of dubious scientific status are invented-and treated.
4) Inadequate media scrutiny
5) An assertion that "natural" remedies are necessarily safer, gentler, and more efficacious than those of technological origin.
PSYCHOLOGICAL FACTORS:
1) The will to believe
2) Logical errors – We as humans have a tendency to mistake correlation for causation. The disease may have just run its natural course, or it maybe cyclical with waxing and waning. Some people see the used alt med as an explanation for their recovery rather than these possibilities. Sometimes alt med and conventional treatment are both used, and quite often we see alt med getting credit for something achieved through conventional medicine.
3) The placebo effect is a strong convincer.