If the consumers didn't buy the supersized (is that a word?) products, the shops wouldn't stock them.
This is why you see so many fat people nowadays.
I recently went to dinner at a friends home. The friend and his family have always been rather chunky, which he has always claimed ran in the family.
Sitting down to dinner was a shock, the fruit starter was enormous (I was full then), followed by steak and a mountain of vegetables. Fortunately I don't eat meat (don't like the taste) so only had the vegetables to contend with.
I was tempted by the cheese cake afters, but feared I might explode. Then there was cake, followed by cheese, all of which I declined.
The next day, my friend asked if I was alright, as I hadn't eaten much. I explained that the portions were much bigger than I was used to, but I don't think he got it.