GroupOn: a license to print money

I submitted the article and must add that the data in it is rather unbelievable.

A different article has GroupOn's Average Revenue per User at 8.6 USD http://www.tnl.net/blog/2011/07/24/how-much-is-a-user-worth/.

One more article has the average revenue/subscriber at 9$ http://www.dmnews.com/groupons-q2-revenue-rises-but-net-inco...

This is still 4 times more than LinkedIn's average Revenue per User. Where as Linked in has a valuation 47 times the Revenue/User, GroupOn has "only" a valuation of 31 times the Revenue/User.

Assuming the data is correct, I really don't understand the "GroupOn bashing" in Hacker News comments. All of the last articles about GroupOn I read where predicting that this Ponzi-scheme has no future.

Is there some fundamental metrics I am missing? Or is GroupOn really a very profitable business once they get the expenses under control?

There is a claim of ~$80 per "Active User", but what is an active user? The article conveniently ignores those figures.