The BMJ paper discusses the positive influence which celebrities can have in highlighting health issues, but cautions against celebrity 'quacks' whose advice is listened to, even when it is dangerous, if adhered to. The question is 'Why do celebrities utterances and endorsements carry so much weight even though they lack any evidence, qualifications and specific experience?' The paper draws on economics, marketing, and psychology literature to provide an answer.
One of the reasons is that the public are bombarded with competing information and in order to make sense of that information:
people naturally look for signals that indicate one source as being more credible and effective than another. Owing to the vaulted status of celebrities in society, their endorsements act as signals of superiority that distinguish the endorsed item from competitors, encouraging people to change their health behaviors accordingly.
[Celebrity] credibility may stem from the halo effect of celebrities' success, which biases people's judgments of celebrities' other traits and gives them a cloak of generalised trustworthiness that extends well beyond their industry or expertise. Celebrities are in turn perceived to have greater credibility than their non-celebrity counterparts, such as doctors, despite having less medical knowledge and experience.I don't see the problem of celebrity advice being isolated to the medical world. I also feel that 'celebrity status' can be more widely defined - isn't it something about putting someone on a pedestal. I have frequently observed the advice of procurement specialists being swallowed up in the aura of 'celebrity' status.