To answer that question, a gambler can get out of his addiction by replacing gambling with something else that's lucrative. Gambling itself isn't a bad thing but when it becomes an addiction it can be very destructive. Quitting is not an easy journey, some might even consider it impossible but if you are determined and consistent with the aim of making a change you would definitely overcome it
You are absolutely right about the determination to give up addiction. If a person does not understand that he is in a difficult situation and wants to solve the problem, then it is absolutely useless to offer him help from the outside. It would be best to contact a specialist in this field. Provide timely assistance to the player and constantly conduct rehabilitation for a long time, without which it is simply impossible to do.