I do actually understand your point.
I guess my analogy would be the term Yankee. It was originally a derogatory term for the colonists, and is still widely used around the world as a derogatory term for Americans. But most Americans will, when called Yankee in a derogatory way by a non-American, will have a "Yeah, and proud of it!" attitude. At least that's the way it used to be.
(Inside the country with all the north/south mess I realize it gets muddied, but I think you get my drift.)
So, if another Trek fan calls me a Trekkie, well hell yeah. And when a non-fan calls me a Trekkie, usually in a snide manner, I don't say, "No, that's Trekker." I say, "til I die, buddy, til I die."
Then they usually look a bit confused because they were trying to irritate me and it didn't work. B)