I already wrote above that I am not an expert in this field. But I personally believe that no one can be cured by force against their will. You can take a person against their will to various clinics, treat and control them. But if the person does not want to recover and get rid of the attachment to drugs, alcohol, gambling, then he will return to his previous occupation after some time after treatment.
But if a gambler is already out of his mind, he will have to be force to go under rehab to be cured, and though it could be against his will, but eventually he will realize that he needs to cooperate to live a normal life. Problem with addicted gamblers is they are not thinking straight anymore, so sometimes a force is needed for them to separate from gambling which is the source of their addiction.
Rehab gives them a good reason to live a normal life, from that point there is a good chance that self will start to bring something out from their mind. If they'll let the process to continue and those bad things that keeps circulating inside about gambling will be flushed out, then new sets of things to do will bring the person new reasons to live without gambling to accompanied.