Anyone who describes themselves as a brony is using the term wrong, it was supposed to be used by bronies talking to other bronies but then someone decided it should be a name for guys who like ponies.
it was originated as a name for guys who like ponies, by the guys who liked ponies you numbskull.
but of course, once someone's own nickname becomes derogatory, you'll get a bunch of people denying to the death that they're those sick "bronies", but just mild-mannered "pony fans".
same thing happened with weeaboos and furries.