Whether they know it or not, people make their dietary choices in large part because of the specific psychological effects of the various kinds of food and drink available to them. This includes not only substances like coffee and wine, which most people seem to understand have mental effects which translate to altered states of consciousness, different tendencies in thought and behavior, etc., but also includes foods like grains and fruit, which the average person wouldn’t imagine are psychoactive. If one quits rice, bread, pasta, apples, oranges, and all other foods that people are drawn to because of the high concentrations of starch and sugar, and instead eat only fatty meat and non-starchy vegetables (as Jordan Peterson does nowadays), then one’s psychological parameters will change. It’s not just a physical affair; certainly going off of grains won’t cause as pronounced of a sobriety as going off of a substance that’s popularly called a “drug”, but it’s categorically identical—though that’s not to say that drugs are “bad”, grains are “bad”, or anything like that, but rather that they all have effects on psychological parameters, for better or worse given one’s goals.
I came down with a case of testicular cancer when I was 21 years old. When I noticed an unusual mass on my right testicle, I scheduled an appointment with a doctor. I had some tests down, and was quickly sent to a surgeon who recommended surgery to cut out the infected testicle. He said he expected that I would also have to undergo chemotherapy, but fortunately after the surgery it was found that the cancer hadn’t spread elsewhere. I was cancer-free at least for the moment; I was told that statistically I had a 1/5 chance over the course of the subsequent 5 years for the cancer to show up somewhere else in my body (meaning I would have to get chemotherapy), along with a 1/20 chance of a new case of testicular cancer appearing in my left testicle (meaning I would become infertile, have to go on hormone-replacement therapy for the rest of my life, and so on). I had been given a taste of catastrophe, and it became nothing short of one of the biggest wake-up calls of my life.
Common knowledge is common not only because it’s within the intellectual grasp of the average person, but also because (metaphorically speaking) the forces of cultural evolution consider it to be useful to be widely known. There are plenty of complex phenomena which are broadly understood, and no shortage of simple facts which escape almost all people. It’s tempting to think that if the average person would benefit in their own life from knowing a certain fact, and that fact requires little intelligence to grasp, then the average person would know that fact. But this absolutely isn’t the case. The memetic system works for the society, not the individual. Widely held beliefs are widely held because they’ve been found (rightly or wrongly) to be beneficial for social cohesion, harmony of interests, and other factors which determine the success not of any given individual, but of the group as a whole. If keeping a fact from the individual harms them but makes it more likely that the group will remain stable, defend against invasion, and spread its norms to the far reaches of the globe, then that fact shall remain a secret, no matter how simple it is once grasped. And if propagating a falsehood again harms the individual but benefits the group, that falsehood may be propagated. The yardstick of ‘truth’ in a society is intimately entangled with group-level interests. What’s beneficial for the individual is often drowned out. The hivemind only tells you what it wants you to hear; anything else you must figure out yourself, only to be forgotten upon your death, as your hard-won understandings will remain underground as long as they threaten the supremacy of the collective consciousness.