Addiction to something happens because the sufferer feels comfortable, full of satisfaction (dopamine effect) when doing that. slots feature amazing animations and also great prizes easily if the player is lucky. I don't like slots but for lottery and soccer betting, I really love and feel addicted 
Just because it's easy to do doesn't mean you need to play it every day and that's what most people became after they suffered such addiction from playing slot machines. some of them are buried in debt because of these small matters that they could have avoided if they remained patient about their life. Slots are addictive because the environment where they put them has lots of people enjoying what they are doing at the moment but in reality, most of them are soon to suffer some serious depression when they lose everything they have in this tricky game. slots are indeed addictive if you are to give in! this basically will depend on the person himself to what extent he will dwell on this gambling activity. if he doesn't contemplate on what's going on with his life, he can really go deep into this game. and it will be too late before he understands that he's in terrible situation. but he needs to address his situation if it is already affecting his health, finances and his relationship with his immediate family.
It's already been proven that slots machine are more highly addictive than playing other games in the casino, and that is because of there graphics and lights that will really stick into the people's brain, especially that golden-yellow dollar sign. But, I really do agree that even if it's addictive, it's up to us how we counter these situations and make the proper mindset before we decide to play these machines because if we just let ourselves gave in then I'm afraid that a terrible situation is already approaching our way.