Well, in my own case, I trusted me, which is why I did not die of melanoma. It only took 4 physicians before I found one who would do a biopsy, which proved me right 
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In my daughter’s case, I trusted the Internet, so she is neither blind nor heart-damaged.
But honestly the question’s rigged. You shouldn’t blindly “trust” in a white-coated hierophant any more than you would trust in a black-robed priest; in both cases, they are just people with a modicum of training, and not magically powered infallible oracles. At least the Internet is a bunch of people, but it’s still just people.
