Whether people believing in a hypothesis is evidence for the hypothesis depends on the hypothesis. If the hypothesis does not contain a claim that there is some mechanism by which people would come to believe in the hypothesis, then it is not evidence. For instance, if people believe in a tea kettle orbiting the sun, their belief is not evidence for it being true, because there is no mechanism by which a tea kettle orbiting the sun might cause people to believe that there is a tea kettle orbiting the sun. In fact, there are some hypotheses for which belief is evidence against. For instance, if someone believes in a conspiracy theory, that's evidence against the conspiracy theory; in a world in which a set of events X occurs, but no conspiracy is behind it, people would be free to develop conspiracy theories regarding X. But in a world in which X occurs, and a conspiracy is behind it, it likely that the conspiracy will interfere with the formation of any conspiracy theory.
Whether people believing in a hypothesis is evidence for the hypothesis depends on the hypothesis. If the hypothesis does not contain a claim that there is some mechanism by which people would come to believe in the hypothesis, then it is not evidence. For instance, if people believe in a tea kettle orbiting the sun, their belief is not evidence for it being true, because there is no mechanism by which a tea kettle orbiting the sun might cause people to believe that there is a tea kettle orbiting the sun.
Bad example. In fact, the example you give is su...
r/Fitness does a weekly "Moronic Monday", a judgment-free thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. I thought this seemed like a useful thing to have here - after all, the concepts discussed on LessWrong are probably at least a little harder to grasp than those of weightlifting. Plus, I have a few stupid questions of my own, so it doesn't seem unreasonable that other people might as well.