Groupon - dud or DUD

I know there's a Groupon copy thread but I wanted to save this one strictly for the business alone.

Read some articles about them - they take anywhere from 50% - 100% of the revenue from the Groupon. And sell it by assuring the business owner that most buyers spend more than the value of the Groupon each visit (a claim some that have unwittingly used the service say is bogus).

Their model tends to be selling more money for less money. How is this legal?

http://www.mygovcost.org/wp-content/uploads/2010/09/capitalism.png

Stock down to $10:
http://www.thestreet.com/story/11514049/1/groupon-plunges-as-board-members-reportedly-leaving.html

Ding Dong, Daily Deals Are Dead - The thrilling demise of Groupon’s crummy business model.: http://www.slate.com/articles/technology/technology/2012/08/groupon_earnings_report_the_daily_deals_site_s_crummy_business_model_is_finally_dead_hooray_.html