Philosophically, the Sundance Film Festival's most important goal is to give independent films from around the world a venue in which to be seen by enthusiastic audiences, but there's no denying Sundance's other major function: to help the filmmakers sell their movies to distributors, who can then sell them to the movie-going public.
For the industry, Sundance is like a big ol' bazaar, where the merchandise is of varying quality and you're free to browse before you buy. You might get something at a bargain price and turn a handsome profit when it goes to theaters later on; or you might pay through the nose for something you're sure will be a hit, only to lose your shirt when it tanks. It's always a crapshoot (often heavy on the crap), and the only way to know for sure whether the purchase was shrewd is in retrospect.
So here's some retrospect! You'll note that it has nothing to do with quality -- all 10 of these movies are good. Yet somehow, their fates ranged from the miraculous to the tragic.