Imagine you have a pub: It's successful and busy so, if the odd customer comes in who is down on their luck, you let them drink for free. But of course, they tell their mates, so more people down on their luck come to your pub for free drinks. And they tell their mates... ...until half the people in the pub are drinking for free and the pub is struggling. What do you do? Put your prices up for the dwindling number of people who are actually paying and keep letting more people drink for free? Or Set limits on number of people who can drink for free? Or Go bust? Or ?