I actually remember learning about this at university. People gamble and when they win, the frontal lobe produces hormones that are almost like a drug. This is the reason why people gamble. It's not an obsessive behavior. Casino know this and use it to their advantage.
gambling its a psicological trap, this game give to you adrenaline rush
Basically adrenaline will get stir up on exciting things. The hidden excitement of gambling is making huge profits. When you believe that you can make profits from gambling then you will end up in addictions for sure.