Belonging to a fandom or other special interest community is typically something that is done through self-identification, which is different than identities that are not chosen, but still part of a broader idea of identity. There are plenty of examples of these self-chosen identities: Trekkies, Potterheads, Bronies, Cumberbitches, etc. Simply watching Star Trek doesn't make you a Trekkie though, it's a label people apply to themselves when they feel invested in that thing and want to be part of a community of people who feel the same. That's all. I also hate to tell you that there are themed sex parties at Star Trek conventions too, so does that make being a Trekkie a kink? Is doing the Vulkan salute and telling someone to "live long and prosper" in public forcing that kink on others?