I agree with waverider.
BPD first appeared on my radar when my wife was given a formal diagnosis upon intake into a DBT program. She had long-standing diagnoses of anxiety and depression and a tentative diagnosis of bipolar disorder. She came back from her DBT program and told me "oh, I have this new diagnosis... .borderline personality disorder."
It was a few months later when I began to research BPD and experienced that shock of recognition that so many of us have gone through, as suddenly the pieces of our lives began to fit into a pattern. Not long after that, I mentioned the BPD diagnosis to her when we were talking in the aftermath of one of her dysregulations.
She flatly denied it. "I don't have BPD. All of my therapists know that. They just gave me the diagnosis for insurance purposes."
This was a stunning reversal to me, and I discussed it with our marriage counselor. He told me her story made no sense -- if anything, insurance doesn't like to pay for treatment for BPD unless it is comorbid with another diagnosis, like depression.
Later, my wife changed her story again and accepted her BPD diagnosis (pretending her denial of it never happened), but told me that it meant that she was not responsible for her outrageous and hurtful behaviors.
Ironically... .BPD would be one of the DX's that one would not want to asses for insurance purposes.