Innumerable hours of research into "causes and cures" reveals no conclusive consensus. A Google search of "Addiction" reveals a plethora of experts, all embracing their own theories, based on conflicting evidence, and all solicitous of funding.
Bottom line: you do not want to get caught up in this maze. It's a
lifetime commitment and there is no end to how deep the rabbit holes go.
It sounds so simplistic but it is easier to "Just Say No. Initially, drugs and alcohol make you feel really good and relieves the stress, but be careful, it's a trap!
Work out your own salvation. Do not depend on others. ~Buddha
Proponents of the choice model of addiction argue that the consumption of drugs or alcohol is a choice, and that just as people can choose to take drugs or alcohol, they can choose not to. Under the moral model of addiction, people addicted to drugs or alcohol are considered weak, with no willpower or other moral failings. But... People's decision to start is voluntary of course. However, once you start, subtle changes begin to take place in your brain and there's no telling where this will take you. Some people are able to indulge in alcohol or experiment with drugs and never seem to suffer any negative consequences. Others are drawn right in and are unable to control their use, it takes over their life. Russian Roulette.
The moral model ignores all the scientific evidence including genetics,
neurobiology/pharmacology and twin studies, which indicate addiction is more than a bad choice and that addicts are not "Bad people trying to
get good, but sick people trying to get Well. We overcame tobacco through education not punishment.
It's always so inspiring to see a patient after an intervention. They have lost that emaciated look of Jim Henson's Gelflings after having their "Vital Essence" drained, in the movie Dark Crystal. Their health is restored, they appear "Refreshed", they look like a totally different person. Addiction is demonic and deceptive. It promises pleasure, then steals the "Vital Essence," the potential, and leaves a smoldering phoenix unable to rise again.
We do not do what we want and yet we are responsible for what we are - that is the fact. ~Jean Paul Sartre, Situations, 1939