Addictions are the person's (or society's) way of avoiding emotional or physical pain. Pain that often originates from one's childhood (abuse, neglect, untrustworthy caregiving) or trauma at any age.
Addictions show up not only in drug or alcohol abuse but in consumerism, sex, power-seeking, gaming, gambling & self-harm.
The following video explains this well.
Punishing the addict only adds to their inner pain. Yet not addressing their addiction is equally unhelpful.
It is very important to start by sharing your perspective and sadness/alarm but without judgement.
By loving the person and noting how their addiction is preventing a healthy relationship with them, while earnestly conveying through words and actions that you wish this to change a seed is likely being planted.
Being consistent with loving them, not their addiction, waters that seed.
It usually takes a community to help a person feel loved and a valued member of it.
Invite others known (or even not known) to the addicted person to participate in reaching out through loving yet accountable ways, loving the person but not their addiction.
For high quality relationships and a life truly worth living.
Don't put it off any longer.
Link to Ian's profile on the B.C. Association of Clinical Counsellors website