"they" are afraid of it for the same reasons they are afraid of LSD or any of the so-called hallucinogens.
because it makes people less susceptible to bullshit! it creates free thinkers and that cannot be allowed.
alcohol is ok because it turns people into numbed out monsters.
prescription mind altering drugs like prozac are ok because they turn people into compliant zombies.
but we just can't have people running around exercising their minds any time they want to.