I think "people" needs qualification here. I regularly encounter people who think such and such a discovery is going to be a magic bullet to cure cancer, or allow FTL travel, or some other major breakthrough (but those two most of all, I think.) So far, they've always been wrong, but that doesn't stop people writing articles on how this not-even-replicated finding is going to be the one to revolutionize our world forever.

Many people become biased against the idea of magic bullets because so many other people aren't, and so they're exposed to numerous prospective magic bullets, none of which actually work.