Personality disorder is not a mental illness, it is a character disorder. The disordered are ego syntonic not ego dystonic, which means, they see nothing wrong with themselves and do not suffer any sort of neurosis or worry about themselves, do not suffer anxiety about themselves like the latter, nor any sense of failure. They are not suffering. And nobody's making fun of mental illness and a 'failed life'. Her life did not fail, she did. She chose to murder. Savagely.
I disagree, choice is what it's all about. And responsibility. Those are the priorities in a civilised, mature world. Not feeling sorry for the bad guy without conscience. Not making out the perpetrator to be the victim.