I'm amazed anyone bought this
Other web 2.0 stocks look overvalued because of the mindless herd, but their business model is plausible.
Facebook and Linkedin are overpriced, but they're otherwise sensible businesses.
Groupon was a scam from beginning to end. There's no sustainable business model and so they're not a going concern. That means any p/e ratio above 2 or 3 is overvaluing them (let alone a billion dollar valuation when they're making a loss).
Any of the potential investors for whom that was too complicated should at least have done a little research into publically available concerns about Groupon's major shareholder:
I have some sympathy for non-tech people who invested in Facebook (not too much, but some) but anyone who put their money into Groupon was essentially putting their money into a pyramid scheme with publically available information to show it was a pyramid scheme and a clear indication that the IPO was the break point at which the important people would stop trying to pretend it was a business.