They're not trying to be different or make an impression of themselves. If anything, the only people I ever see talk about pansexuality are people who aren't pansexual.
In the real world, nobody talks about pansexuality outside of Tumblr, where people think having a blog makes you a sexuality studies major
sure. but it's for people who need attention because they can't find anything else unique about themselves. so they resort to some stupid term to define their horny fantasies.