I believe the "drinking the kool-aid" term stems from the cult led by Jim Jones that offed themselves in, IIRC, the 1970's, with cyanide-laced kool-aid, after a congressman was shot by some of their members. The true believers drank the kool-aid willingly; the skeptical ones had to be forced to drink it. IIRC, a few were shot.
I can only think of autos as having numerous fanboys who blindly drink the combination of marketing and true-believer hype, with the exception of the already-mentioned Taurus Judge revolver.
Some say that believers in the .357 Magnum are buying into the marketing hype, but as one who actually used the .357 in a shooting back in the day, and saw the tremendous wound channel, there is substance to the support for the .357 Mag. Down here in Texas, we knew the .357 Magnum worked well, without needing to read anything written by Mas Ayoob, Evan Marshall, or Ed Sanow. (To be clear, I like Mas and Evan; not trying to start any fights here!) My wife is a forensic investigator, and has commented graphically on the wound channels chopped by both .357 Mag and 357 SIG, as well as the immediate effect, based on blood spatter evidence at the scenes. (Yes, "spatter," not "splatter.")
To be clear, many folks DO give the .357 Magnum too much credit, likening it to a science-fictional death ray. It is not. It does, however, bore some impressive holes into human bodies.