In my opinion, someone gambling for fun understands and accepts that they are likely to lose the money they wager. The money spent is viewed as the price of admission for the entertainment experience, not an investment or a serious attempt to get rich. Losses are seen as part of the game, not a catastrophic event. 
Those who accept gambling as fun, which is also seen in their gambling activities. I have seen a gambler who does not gamble regularly but when he goes out somewhere far away or holyday celebrate, I have seen him deposit. He deposits some money in gambling with the intention of losing some money at that time. He knows that he will lose but if he wins, it will be pleasant for him. If gambling is accepted as fun, gambling can never be a cause of harm for those who can do such behavior. If a gambler ever gambles for winning or for the sake of making money, then it is not fun, but his chances of losing increase greatly.