A long time back, I asked our extra-special-omg-I'll-never-forget-him-incredible waiter at CR about how Disney made money with dining plans. at the time it was still "Magical Wishes" that you spent, but he said something that I think is pretty fitting here. We'd asked because we'd done what most people here do, figured out ahead of time where we could eat and what, to get the most bang for our buck, and we couldn't figure out how, even though we payed for the wishes, Disney made money.
He explained that even people who get dining plans still spend an average of $25 per person per day at the parks on food items, between bottles of water, a quick ice cream, a cereal breakfast that they didn't want to waste points on, an appetizer at a bar, etc. Many of these people also never use all their points by the end of the vacation, so that is "free money" to Disney. Also, many people get the dining plan but don't take full advantage of it, so they do not always order the most expensive thing on the menu, or they spend points on smaller items because they are not very hungry (then he proceeded to thank us for ordering expensive because of course his huge tip was included in the gratuities section of the bill, paid of course!

) . Though there are people like me (and probably many people here!) who know how to get a huge bill at a restaurant and check it all off to a dining plan, it accounts for about 15% I think he said of diners; most eat "average".
But it was just one thing that he said as he explained it all that fits: "I bet Disney could give these Magical Wishes away and they'd still make money." with the free dining, it looks like he was right!