Sure he saved money on groceries but that only counts if you ignore what it costs you everywhere else. Eating the same thing four nights a week for six months is a real cost, just not one that shows up on the receipt. Boredom makes people quit, and quitting is expensive when you already bought twenty pounds of beans. Plus beans alone aren't a meal unless you're adding stuff to them, and that stuff is where the money sneaks back in. My take is he saved money in spite of the beans, not because of them.