Probably because the human brain evolved long before there were any large, well-run meta-analyses of scientific studies. 50,000 years ago, if someone made a cl

Probably because the human brain evolved long before there were any large, well-run meta-analyses of scientific studies. 50,000 years ago, if someone made a claim, and you had experience to the contrary, it was important to your tribe to hear the counter-evidence, lest they start making decisions without all the currently-available information. Our brains may rationally absorb "this effect holds true for 95% of participants, and if it doesn't for you, that's within the range of normalcy (the other 5%) but doesn't invalidate the findings". But our instincts aren't as nuanced.