Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

In a competitive market, why is movie theater popcorn expensive?
People have moods, that mean they don't have the same level of demand for luxuries every day.  There might be some days when I'm feeling a bit poor, or feel like I need to save money, and the price I'm prepared to pay for a box of popcorn might be 50c.  There might be other days, for example, the day after I receive my wages, when I feel rich and I don't care how much I spend on things.  On such a day, the price I'm prepared to pay for a box of popcorn might be $10. Now, when a supermarket sells popcorn, they're not really able to price discriminate between these two groups.  People come through their doors in all kinds of mood, so the profit-maximising price for popcorn is going to be somewhere in the middle. But the only people who go to a movie theatre are people who are already in the right mood to spend money on needless luxuries.  So the very fact of being in a movie theatre means that a popcorn stall, whether affiliated to the theatre or not, is open only to the high-spending end of the market.  They have already caught me when I'm in the mood to spend, so their profit-maximising price will be much higher than that of the supermarket.