Gambling is very addicting because of the fact that its very enjoying and you can do a lot of things too with gambling, its very nice to do it plus its sometimes profitable.
True, we are enjoying on how gambling really works and even you are not that going to focus with profits in gambling. But if you are lucky enough then you have a chance of earning some good amount. And that is what a gambler keeps on gambling again and again when he tries to win some amount whether it is big or small.
The reason why gambling is addicting is that it has rewards, anything having rewards for people becomes addictive no matter if that is costing them even more but people like getting rewarded and i have observed that myself.