I'm going to get the quote wrong but Mark Twain once said (something like) "Give a man a reputation as a early riser, he can sleep 'til noon."
Once you establish something in the collective culture, it becomes very hard to dislodge.
Homeopathy still reeps the rewards from its initial successes.
When homeopathy was first introduced in the late 18th century, it was more successful than conventional treatments. That is to say, conventional treatments were so God awful that just _not_ going to the doctor was a step in the right direction.
Homeopathy is literally nothing more than water. But, because it goes a reputation as a successful medicine, it's dug in like a tick.
Sadly, the only thing that'll dislodge it at this point is having some celebrity's child die due to homeopathic neglect followed by a media circus trial and relentless exposes about this pseudo science.