Obviously I don't know the details of your family, but just wanted to say that many people with substance problems are the victims of other forms of abuse, including narcissistic. If one's never learned good processing/coping mechanisms, the anxiety, cognitive dissonance, guilt, shame, etc is often dealt with through substances. Some narcissists are addicts, but hardly all addicts are narcissists.

And sometimes having an addict on hand benefits the narcissist. Easy target or scapegoat, or someone to prove just how wonderful they are, trying to care for, and help, this unfortunate person.

That's a trip that your family member spoke openly about how the they accept his ways and just do their own thing. That, sadly, really is about all you can do with a narc. But I'll add to that, you do need strong boundaries in place. Boundaries don't set the other person straight, or change the other person directly. Boundaries are a civil way of you finding the edges of yourself, living into and liking who YOU are, and not allowing another person to overstep where they're not invited.