so what is a 'groupie' to you lazy?
i have images of an underage girl overawed by her famous hero begging to be let backstage to be in there and cool and see them and then finding herself way out of her depth, handed alcohol, drugs, etc surrounded by 'cool' grown ups and then finding herself being mauled, not realising that was what she'd signed up for but being way too out of her depth to know how to extricate herself from the situation (not to mention probably a bit pissed and high by this point).
i don't imagine the sex being a mutual loving act or one where her pleasure gets much attention but of being used as a thing to fuck by an adult male who is cool with getting a child who adores them off their face and fucking her before going back to his mates to carry on getting hammered.
is that a groupie? if it happened to your 15yo you'd be cool with it and say well you are a groupie after all?
groupies are what men call girl fans who they use for sex. i doubt it is a category the girl chooses and understands the dynamic of.
if the so called groupies are underage and having their naivety and awe exploited to be used for sex by men then they are abused children. they don't cease to be abused children purely because they like the band the abuser is in.