People can get addicted to anything, remember that Addiction starts when you do something more than usual. it is possible to get addicted to a particular food, most people that get out of shape either get addicted to a particular food or they just get obsessed with eating too much. Even without an addictive substance some people still get addicted to a type of food, same way people get addicted to gambling without using any substance.
Even when you eat too much food, it can get you uncomfortable, there are some non alcoholic drink that doesn't make people intoxicated but when you take too much of it, you can get tipsy. The same analogy apply to gam but we don't care. We over gamble and when we see the consequences of our actions, we now act like it wasn't our fault that we gamble irresponsibly. If only we gamble with the little we can afford to lose, it's going to be a win for casino and the gambler, the gamblers might lose but it wouldn't be at the expense of addiction.
However, I feel this comparison of alcohol, drugs and gambling are different things. It seems many of us in this thread hasn't encounter a close relation that has been addicted to drug abuse. It's one of the worse thing you will want to see your family and friends doing. It's even worse than gambling addiction in my opinion. It kills dreams and everything they work for including the people around them. Never pray to see a close relation addicted to drugs.