The "statistics" will inevitably be skewed in the long term success rates, but you are right. There is evidence that new pathways are created in the brain from drug use, so never wanting to use again for most(if not all) former drug users is a bit like never wanting to eat or have sex or do something exciting again, as a lot of the same parts of the brain are activated by pleasurable activities. It's the same reason crash diets never work long term- anyone can restrain for long enough, but unless you are replacing unhealthy eating habits with healthy ones, it will be an endless cycle of weight loss an gain. IF a person only uses one's willpower to abstain from a drug addiction, one will possibly be successful for a time but generally will fall back to old habits/methods of coping(relapse).
This is why it's so important to address far more than just the physical drug use itself, otherwise jail/prison would actually be a successful drug treatment. One must find other methods of dealing with issues, trauma, and emotions, and probably more importantly, a way to find pleasure in life without the use of drugs, as in natural ways to stimulate your pleasure pathway, which can range from casual things like coffee with a friend, learning an instrument, learning something you're interested in, or more intense things like skydiving, hiking a mountain)