I think that's a reasonable question. The answer is that there are much cheaper ways to obtain the placebo effect here than to give these companies your money.
I also guess without immediate proof that the placebo effect is likely to be temporary and represent no real, persistent change to intelligence at all.... another reason to not give them your money. There are cheaper and much more entertaining ways to obtain "no change to your intelligence".
> The answer is that there are much cheaper ways to obtain the placebo effect here than to give these companies your money.
There might be cheaper ways, but paying money has an impact too. That's why more expensive painkillers often work better than generic ones, despite having identical ingredients [1].
I also guess without immediate proof that the placebo effect is likely to be temporary and represent no real, persistent change to intelligence at all.... another reason to not give them your money. There are cheaper and much more entertaining ways to obtain "no change to your intelligence".