Yep, everyone of us even if you deny it is just a 'baby' inside. We're all stubborn. If you force someone to seek professional help, he would just won't listen or would do the exact opposite of what is told. I think the chance of someone completely leaving gambling is all dependent on his intrinsic drive. If the person didn't want to change since day 1, then he wouldn't be able to leave gambling. He should be ready to let go of everything that leads him to gambling.
Well professional help can to settle a lot of issues. Even those who dont want to go to professional help, there will be activities provided by the professional to let them slowly aware of the bigger pictures. It definitely wont be a one time off that they will change 180 degree. It will takes a period of time to convert the mindset away from gambling. However, all these are useless if there isnt any parents or friends support.