I personally believe that the only true way to be a fan is if you like everything (Well, you do not have to like, more like be familiar with) that has to do with it.
It bothers me when people are like, "Oh, yeah. I'm like a huge Twilight fan! My favorite scene in the book is like when Edward and Bella skip school and go to the meadow! And I love Tyler, he's like so hot! Perfect Jacob."
But I don't think that original fans (or fans before the movie) are any more special or truer or bigger or anything. Yes, we probably know more, are more obsessed and (Yes, a tiny bit more awesome) but we're all still Stephenie's fans. And, hey, maybe the movie got new people to fall in love with the books. All of my friends did.
As for the taking advantage of Twilight/vampires, my personal philosophy is this: JK Rowling taught the whole world to read (thanks, Riddletm) and Stephenie Meyer brought back the Young Adult genre.
Now everything that is being made into a movie is basically young adult (The Hunger Games, Mortal Instruments [House of Night? Maybe?] John Green's books). And that's not a bad thing.
I do agree that vampires are overtaking the YA world (House of Night, Blue Bloods, Vampire Academy, True Blood, Vampire Diaries, Morganville Vampires, ect) and it can get kind of annoying. I also think that Twilight has become instead of YA, more of a transition from, well everything.
There are a ton of people who think that Twilighters are the worst things on earth (We only listen to "good" music because that idiot Stephenie Meyer suggested it or we only read crap (Twilight) and watch Disney Channel/Jonas Brothers constantly. We're 12 year olds.) And some of us might fit in the description above (No offense intended). But many are older women, married even, and some are teens, and yet more are younger children/tweens. My grandmother has read the series!
People need to get over it and accept it. Twilight's a major money-maker/pop-culture. It's not going anywhere. At least for a few years. Oh, yeah, and fandom fights suck. Harry Potter might have been around longer, and a bit better, but that doesn't mean Twilight sucks.
Sorry it's so lengthy!