[mitultiwari]

When a deal appears for a business on Groupon, people buy those deals that day and visit that business later on. That's what I meant by "cash up front".

Yes, I agree with you that barrier to entry is very low. However, Groupon has so many businesses lined up (since they have maximum reach) that Groupon can choose the best deal to offer to customers. That's the advantage Groupon has compared to others.