"It is your fault, just don't do it again. Oh, you did it again, well just don't. You keep doing it, somehow you can't seem to stop, but you should.."
Helpful isn't it.
Then your friend goes home and drinks alone...
Addiction is largely driven by neurodevelopmental disorders (ADHD, ASD, MDD, sleep disorders, and many more), psychological disorders (anxiety, OCD, and many more), or both in combination. Most folks don't want to be addicts. At the heart of addiction is executive dysfunction caused by the above conditions, exacerbated by stressors. You treat it like any other mental health problem: therapy, medication, support systems, and a society that cares for its populace.