Looking at this article from some time ago [1996] with the invention of the
30L Coke, did it take off?
Coca-Cola Introduces New 30-Liter Size | The Onion - America's Finest News Source
It was being labelled as "family size". Hell you would surely need a huge family to get through that in the period prior to it going flat.
If we, as a family ever buy coke, which is rarely i might add, a 2L bottle will suffice and last a good 5 days.
A little self control is all that's needed, but obviously some people are devoid of this trait.
So perhaps product quantity should be looked at?
Paul.