Sorry to shit on your thread - but I have a brother-in-law who did a monster a day for about a year... now he's got severe colitis and is in and out of hospital every few weeks. I wouldn't drink that junk even if you were giving it away for free.
Maybe offer other coke products?
Moderation is good to have. It doesn't apply to everything (like cigarettes), but a monster a day might be a bit much. They also say that if you chug a 2-liter of diet soda every day, you'll eventually develop cancer

But doing anything too much these days causes cancer, it seems.