i think gambling addiction is usually one of two mainly things, knowledge that you have won before, and can gain again
People thin that they can win with gambling and that is why they keep gambling on and on until they win again. It is also not much that you have to do.
The fact that you can play games and win money is enough reason for some people to gamble.
Yes they are thinking that they can win and try it over and over, the fact is that it gets addicted due to that and people also get greedy and want to win their money back, what of course never is gonna happen.