Its possible because the movie was panned by critics, it deterred others from seeing the movie. Only those loyal to the book & the book series itself went to see it, apart from the few that like dragons. For me the movie was good, but its just my opinion. I read the entire series and its my second favorite book series. But the first book dragged on for several chapters, basically at some point where Brom & Eragon are on their journey up till the point where Eragon & Murtagh arrived at the Vardan camp. From that point forward, the series is a fantastic read. Perhaps because of the slow start of the story where it dragged could have played a part in the film's lack of success. Just my opinion.