Because branding, red bull makes it hard to get their stuff which creates demand, same kind of thing as jiberish, they don't just sell J-crowns or Red bull stickers, instead you have to earn it. This makes kids think the brand is even cooler. I mean how many kids do you see with monster stickers who are spancerized. Red Bull increases the value and prestige of their brand by being careful who they let it be associated with.
Also, drink water, those guys are awesome!
I have nothing against energy drinks though, I would way rather spend money on red bull that goes towards rampage and paying guys like Sean Petit and Brandon Semenuk (and many others) than on Starbucks coffee where my money goes to who knows what.