I get so tired of hearing "the addict won't change unless he wants to change."  It's true, and also trivial.  If he changes, that proves he wants to.  If he doesn't, that proves he doesn't.  Can you see how circular that is?  "Want" stands for a concept that is actually very hard to define, much less operationalize.  

Peggy Billingsley is the only one (so far) in this thread to put her finger on the central fact about addiction: like other mental illnesses,  it invariably involves intense internal conflict.  The addict is still himself, the person you've always known . . . and yet he isn't.  A sort of shadow self seems to have taken control of his behavior.  As countless recovered addicts and alcoholics can testify, it's possible to close the door on that false self.  Most of them acknowledge that some sort of intervention was crucial to their recovery.  As Johann Hari put it in his excellent study of addiction, "The opposite of addiction isn't sobriety but connection."