Some of the BPD chat has made for difficult reading. My Husband was diagnosed with BPD before we got married. He's medicated for the depression, anxiety, and OCD that have come with it, and did have some therapy at one point.
He's previously been quite impulsive. Things like tattoos and piercings, big purchases like a car, booking holidays without asking me first. We now have a rule that he has to stop and think "can we afford it?" And "what would my wife think about this?" And generally he does stick with it.
He finds it hard to keep friendships going, because as soon as he gets comfortable with people his brain tells him they're not really his friends, and they don't really like him. He's pushed friends away in the past, because in his head that's easier than them abandoning him.
He doesn't drink or gamble at all, because he knows that once he starts there's a chance he won't be able to stop.
Despite all the issues, he's a good man, and a wonderful father. He's worked so hard to make sure he is more than his diagnosis. Not once in the 16 years since we met have I known him to use his mental health as a weapon, or a tool to excuse his behaviour. He would be devastated if he thought anyone was judging him because he has BPD.
I'd say that anyone who is enough of a dick to brush off their dickish behaviour with "I can't help it coz I've got this diagnosis" would still be a dick without that diagnosis.