Again, a person can only be helped if they want to be helped. If they don't think there's a problem, then they really can't be helped. The most you can do is show them the consequences of their actions, and even then, they may still think that everyone is "picking on them."
My dad never thought that he had a drinking problem, and he would often mix alcohol with drugs. He is convinced that the police and court systems simply don't like him because he "has dirt on them," or some such crap. He thinks that they're treating him badly because he knows stuff about them that would cause them to lose their jobs. It never once occurred to him that his problem was drugs and alcohol. Never once.
And then there's my mom, who is working to get her diagnosis of bipolar overturned. When she hits all the diagnostic criteria with a sledgehammer and then some. When her manic moments and extreme mood swings have gotten her in trouble with the law. When she has a history of delusional behavior and psychotic symptoms. And she refuses to take her medication because she doesn't want it taking away her "highs," even though she is mean and nasty, manipulative, and downright abusive.
I may not have a degree in psychology, though I did take the time to study the condition and become versed in the diagnostic criteria. If my mom manages to fool a psychiatrist, then that person is an idiot, though I cannot fully blame them, as they haven't any access to my mom's history.
They should give me a call. I have enough anecdotal evidence for a book.