Richard McKenzie, an economics professor at University of California-Irvine, says theater owners mark up the snack so much because they don't make a profit elsewhere.
McKenzie, author of the 2008 book "Why Popcorn Costs So Much at the Movies: And Other Pricing Puzzles," says that out of your $10 movie ticket, only a tiny percentage goes to the theater's profits.
"Popcorn is what pays for a lot of stuff in the movie theater," McKenzie says. "A lot of theater owners tell me, 'I consider myself working in concessions, not movies.'"
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