Because movies, tv shows, and books with fictional things exist. People think they can fly because of things like Harry Potter. Some think Thor and Loki are brothers because of Avengers. Some think they can be a fairy because Winx Club. But these things are meant for our entertainment, not to be taken seriously. Fantasy is a wonderful way to let your imagination and creativity flow playing video games and such. It only becomes a problem when fantasy gets mistaken for reality.