So, the bum might be drinking the same thing as a billionaire or a slightly different version. IMO, what's more interesting is that where wine, beer and even water have a fairly stratified market soda is just store brand vs name brand.
http://maineroot.com/ (uses fair trade organic sugar) https://www.boylanbottling.com/ http://reedsinc.com/
Personally, I never drink Coke, Pepsi or Dr Pepper products any more. A large part of the cost of those products is relentless marketing, shareholder dividends, and large corporate salaries. They no longer seem to care about delivering a quality product. How can they sell something called ginger ale if it doesn't actually have any ginger? For variety and depth of flavor any money I spend on soda is spent on craft soda.
I agree with you, in that spending money on quality products is "voting with your wallet," and overall, a good idea.
Be the change that you wish to see in the world.