> anyone who has looked into the evidence around nootropics can tell you that pretty much nobody wants to study that

There's a class of areas where lots of non-experts are interested, but doing studies large enough to detect modest effect sizes with high confidence is too expensive. Nutrition can do either large survey studies, or small controlled experiments. Exercise researchers often have to work with a small number of untrained participants. I would love a citizen science platform for large studies of low-risk interventions operated like a multi-armed bandit setup. "Oh, you're interested improving working memory? Follow regimen X for 90 days and do this working memory test every week." I feel like the hardest parts are getting participants to adhere to their assigned intervention, and preventing participants with a pre-existing agenda from joining.