I believe fun could be part of the addiction because if you are having fun, you always want to do it
Fun is definitely wont be causing addiction. Let me give you an example to brief in, why do you hink there are so many pro hardcore dota player? Do you think they play for fun? No they dont , they play to win and become the best. Plus that they are making money from it. Now do you see the point of it? It is about making money and nothing else
It can be a factor also when you are enjoying all the times you play, and it could cause addiction. The feeling of the dopamines in your brain, rising higher, it causes to feel happiness, and it could lead to the addiction itself. Gamblers play because of the profit also, not just to become the best. Formulating different techniques could lead themselves to the best part.
So what makes a gambler happy? it's winning of course.
The other guy is right, fun has nothing to do with addiction, it will always be the money that is involved in betting that makes it addicting whether we win or lose. When we win, we feel happy, and that makes us bet more and stay in the gambling site for long, when we lose, we still have the reason to continue as we want them to pay back all that we lose.
I would agree that fun is a reason why people gets addicted to gambling if there is no money or bet involved.