when your glasses are broken, you go to an eyeglass store.
then they ask if you want blue light blocking.
sounds good, please.
you pay an extra $50.
it can happen.

you must have prior knowledge.
$50 is a lot.
https://en.wikipedia.org/wiki/Blue-light_blocking_glasses

i think the most expensive pseudoscience is blue light blocking glasses or computer glasses.
you're most likely to pay for.
it's more expensive than mbti or hydrogen water.