Facebook walking away from the money made sense. Groupon walking away from that kind of money will go down as one of the stupidest decisions ever made. Our kids will read about this shit in business books about what not to do. There is nothing unique or original in their business model and it is too easily replicated. Their value lies in their email list and their media buying data, and I've got to believe that's worth considerably less that $6 billion, not more.