Gambling is basically like a game. And your balance is the score. The main difference of gambling from game is that in a game, your score would only rise. In gambling, your balance decreases or increases depending on the outcome of your bet. I guess that's the fun of gambling together with the fun that's made by the people that you play with.
There are games where you get deducted when you get a mistake or the opponent has done something to you, the difference between a game and gambling is money, yes you can also gamble/bet in computer games but you can't really play in a casino without money even online casinos need bitcoin for you to play. Gambling for me is fun when I am winning of course.