Gambling addiction is not that easy to get rid of, someone who gets deep into this once, they spend all their life trying to get rid of the urge that keeps poking them and forcing them to gamble, and this continues even when they leave gambling, or at least pretend to. So, it's not as easy as it may sound, the urge for an addiction is very strong, and even stronger if the addiction is related to money and finances.
Returning to gambling after quitting is not always a result of addiction. Someone can lose money that is very important to him and due to that anger and frustration decide never to gamble again but after sometime when the anger would have subsided, he return to gamble again. This happens to a lot of people including me, I have stopped gambling many times but always come back. I'm not addicted to gambling because I can control myself but it happens that some losses will make me stop gambling for sometime.