I think those one get addicted the most who actually won some big amount in the gambling one or more times and lost that again so they think that this is possible and in effort to do that again,they keep gambling and hope that they can again win that big amount,but that doesnt matter because they gonna loose it again.
Yes if they lose money in beginning games they will not come back again to play gambling. Because those people will not take one more chance. But Only those who made a big profit in gambling few times those people will become greedy and they will play again to make some more profit. End of the day they will be completed with big lose. So this greedy will make people addict this gambling.
That is the main reason why gambling is addicting, people tend to think that they are going to generate good profit out of it. And when they are earning great there it will build up to their minds that they are going to keep on gambling. And when the time of losing comes what they are going to do is to keep on recovering their losses.