It is possible for someone to become addicted to drugs, but it is not dependent on any one factor. There are many variables that influence risk for addiction, including genetic, developmental, and environmental factors. As someone's risk factors for addiction increase, so does the likelihood that they will become addicted to drugs.
Environment. The environment a person lives in has many factors. This includes family and friends as well as economic situation and overall quality of living. Peer pressure and early exposure to drugs, stress and parental supervision all can have an important impact on someone's chances of developing a drug addiction.
It is not uncommon for a patient to relapse, but that doesn't mean that the treatment didn't work. A patient's long-term health issue should not be abandoned. The treatment plan should be modified according to how they respond. This holds true for all long-term health issues. This is why treatment plans must be reviewed often and modified to ensure they are still relevant to the patient's changing needs.