In that case a kid could have a question, why someone has to play with real money just to have fun. This question sound very reasonable to me. After all, there are lots of other ways to have fun, without risking your money and possibility to end up in debts and with an addiction. What a parent should tell his child about that? I get your point about the necessity of drawing a line between gambling and earning. But my point is what is the argument to support precisely gambling as a way of having fun?