Beat me to it. Before we were obese, we were already smokers, alcoholics, gambling addicts, sex fiends, violent thugs, opium lovers... if there is anything we can abuse, we will. Animals don't know when they're having too much of a good thing, evolutionary instincts are honed on getting as much as you can today because you could get none tomorrow.
What profits? If they're charging you the same whether you get three refills or zero, that sounds like a pretty shitty way to get people to spend more on soda.
We have free refills in Canada and they're basically just abused by teenagers and poor people so three people can drink from one soda.
How is filling people up with soda going to make them buy more food?
Honestly, I think free refills were invented because soda is cheaper than the fast food guy's time filling your cup. Therefore, they moved the soda fountains to the dining room and just started handing out cups with meals to save money.
