I would say that expensive and long-term rehabilitation is not necessary for recovery. In this case, it is more important that the patient himself wants to recover and leave his harmful addictions. However, if money and time allows you to go through rehabilitation, it is unlikely to hurt.
People would always say this but I think this still depends on that individual. There are those gamblers or people that stopped their addiction by themselves, it sounds amazing and it is true since it is really hard to do that. In my case, I visit one and told me what should I do and they also said that the key is not them but myself. They said that I am pushing a door and that enigma is pushing it back the reason I can't open it, they said that before all of the things I wanted to do, I need to set that door free, let the enigma free and let myself assess what I've done. That just means that we need to accept ourselves, accept that we committed mistakes and we want to make up for that.