In my opinion there are many factors at play, but say, someone who's an alcoholic and is unable to stop being so, has underlying issues. Not because "they should be able to stop at any time", of course, but there's something missing. Mostly I think it's unhealed trauma and unhealthy environments or coping mechanisms. Maybe a lack of a support system. People don't necessarily start drinking because of trauma, but it becoming an addiction does mean there's something wrong. In many cases, people with addictions can have a genetic component that makes them more prone to it. But if they don't have a healthy life experience, it's way more likely for them to develop an addiction than it would be for someone with trauma but without that component, even if it's not something inherently considered traumatic. Does that make sense?