A number of posters have mentioned "the" daily deal not being something they'd use. It appears many Groupon users aren't aware most deals are available for several days.
I'm one that said deals I'd buy are few and far between, and I am well aware that they are available for several days. You also said investors like and trust Groupon- they do today. They just turned a profit for the first time, and there's still a lot to be seen before I would trust them enough to risk having a wedding gift I'd given someone just disappear.
http://www.reuters.com/article/2012/05/14/us-groupon-idUSBRE84D16H20120514