This is actually a proven concept in the world of business called 'Endowed Progress.' It basically shows that if you give someone something for free - they will use that free inertia to go on and make a purchase that they never would have done before. Say a coffee company has those 'Buy 5-
Get 1 free stamp cards, well Marketing studies have shown that if they stamp 2 holes for your first purchase then you are 60% more likely to buy the extra 3 to fill out the card. In another instance - if a waitress brings you a small chocolate with your bill then you tend to tip her 20% more if she would not have done so. This concept is also called reciprocity - and generally mean that those given free coins will in turn pay for more in the future - and the flow of good karma continues :)