Related: medical students' disease! https://en.m.wikipedia.org/wiki/Medical_students%27_disease
I went through the first two years of a psychology degree alternately diagnosing myself with every mental illness under the sun, despite me knowing deep down that it wasn't really the case. The thing that stopped it dead was watching clinical videos of people who really did have serious mental illness. I wonder if the same would work for some of these people, presuming they're being suggestible.
I remember in particular one video of a man with bipolar disorder in a manic phase, who was in his mid-20s when the video was filmed during the late 80s, and who was convinced that he'd been the Rolling Stones tour manager in the 1960s. There was nothing anyone could say to convince him otherwise, and he had all sorts of explanations for the mismatch in dates. We were laughing a bit because it was so clearly delusional, when the lecturer pause the video and said something like "yeah, it's kinda funny, but I remember getting a call from a friend who asked my clinical opinion about the fact he thought that the adverts for a bank on TV were telling everyone he was gay." We got pretty quiet after that.
It chimes with the trivialisation of terms like OCD, which are use very filppantly, but anyone who's seen a clinical video of someone with full-blown OCD, which can be completely crippling, wouldn't use it so lightly.