I'm convinced that malignant narcissists often mess up, and expose themselves, because they overplay their hand. In a workplace, they may drive two or three people out of a job. But when they do it for the fourth time, their aberrant behavior catches up with them, and upper management finally decides that having them on staff is getting too expensive. (At least one-third of all Americans report being bullied at work, at some point in their career. Typically, they are either fired or quit. Hiring and training new employees is costly.)
The bully might have gotten away with serial abuse three times in a row. She likely would have retained the respect of her higher ups if she had stopped at that. But, apparently, she couldn't.
Or, a Queen Bee in a group of Moms may target one of the other mothers. The rest of the woman in the group act as enablers, watching it unfold until the victim bows out of their social circle. However, when the bully tries the same thing again, and then again, she may wear out her welcome.
Narcissists lack awareness of boundaries, so they don't know when to call it quits. They push the envelope so far that it slides off the table. If they abuse once, they'll abuse again, It's the repeated incidents that seem to lead to their undoing.
I've watched this play out, in my own experience with a female narcissist, whom I met at church. In a previous post, I talked about not allowing a morally disordered person to know your future plans, as they may try to foil them. They could try to create trouble for you at the next locale, especially if they aren't yet focused on their next target.
Anyway, a woman who created havoc in one religious setting tried it again elsewhere. But she made a tactical blunder. Typically, a narc will target only one person at a time. However, this individual chose to go after me and another woman, whom was very well known and liked. Being a newcomer, I was an easy mark. But everyone knew the other woman was not capable of all the ridiculous things she was being accused of.
So, if you've been targeted by a narcissist, all you have to do is wait. Eventually she'll slip up.