Traditionally, the most popular movies had to appeal to all segments of the population; kids went, and mom and dad and grandma too. That was true for the films that held the records for the top grossers of their decades (Gone With the Wind, The Best Years of Our Lives, Ben-Hur, The Sound of Music) and for the mega-movies in the pre-Star Wars 70s (Airport, The Godfather, The Sting, Exorcist, Jaws). Along comes this little niche movie; but male boys, seeing it over and over, helped it outperform all the broader-based hits. From then on, Hollywood tailored most of its big-ticket items to males aged 12 to 24. That demographic, less than 10% of the U.S. population, now controls the way studios spend the biggest chunks of their money. Since this is also the fast-food target audience, chains like McDonald's jump at tie-in campaigns.