I think when you are used to a diet of heavily processed food, or a very varied diet, it is hard to conceive of eating so much of one food, but many cultures have and still do this. I'm thinking of some asian countries where every meal is lots of rice and a little bit of something with it. One of my asian friends used to measure how hungry she was by rice bowls ("I'm really hungry today, I could eat three bowls of rice" etc), and some of the asian students at a hostel I was at used to cook up a huge amount of rice and then share the contents of one tin of something like abalone between 4 or 5 to go with it.
On a more personal note, I never used to be interested much in potatoes until I lived in Scotland - something about the cold winters, and needing heavy carbohydrate meals, and suddenly I'm eating far more potatoes, and enjoying them much more too.
