Even scientists fall victim to this all the time. Just go back and look at phrenology and crainiometry for a primer. I would agree that psychology is more prone, however. Ever since Pavlov and Watson, psychology has been trying to prove behaviorism is a thing (it's not). They keep changing the name, and trying to add layers of nuance, but a stinking pile of garbage by any other name...

The most bothersome thing to me isn't these silly will power studies, but rather the whole new fields of "neuropsychology" and "behavioral neuroscience" that are getting so many billions of dollars and one press article after the next to espouse that which we know to be false (and have known since very shortly after Watson). Next week someone will come along and "prove" that the cookie-will-power theory is "correct" because they hooked the subjects up to an fMRI and their brains "lit up" every time they denied themselves a cookie. The truly sad thing isn't that there are no scientists doing psychology; it's that there are no requirements to have any kind of philosophical moorings to get into experimental science.