system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How did blood letting survive as an idea for so long?

From what I understand blood letting existed as a medicine/treatment as far back as Ancient Egypt and didn't stop until the 1800s.
If there's no actual benefits for the most of the conditions it was being used for, how did it last so long?
gpt
Placebo effect, combined with a lack of better options.

People believed it would help them get better, so sometimes they felt better after treatment — even though we know that the “treatment” probably did more harm than good, in all but a minority of cases. There are tons of things we as humans do that have no empirical basis, like knocking on wood, or praying, or wearing lucky underwear; we do them because doing them makes us feel better.

Combine that with the fact that for most of that time, it was kind of bloodletting or nothing. Especially if you were not of the highest socioeconomic classes. People believed it was better to have *some* treatment than *no* treatment, so they went with what they had.

There are tons of justifications for why we started in the first place — everything from women menstruating to hippo sweat — but the reason we continued boils down to “it was the best we had.”