Q: What happens if you let everyone contribute to and take from a Starbucks card? A: We are in the process of finding out, and the answer wasn't what we expected!
Why isn't this just an interesting, unexpected result? Furthermore, condemning this guy is like condemning Lulzsec for exposing security vulnerabilities. Do you think that no one would have figured this out if OP hadn't? He's exposing the vulnerability and sending the proceeds to charity, would you prefer that Mr. Unscrupulous just silently steals it all?