My understanding is that is complicated, and in many cases it's involuntary.
Sociopaths are abusers because they utterly lack empathy, are prone to risk taking to the point where they will harm self and others, and may even lack the brain structures that make empathy possible. Clearly no amount of management training is going to fix that.
Narcissists are abusers because they live in a state of constant severe unconscious anxiety, trying to shore up a very brittle and fragile ego with fantasies of omnipotence and irresistibility. Most people are narcissistic some of the time, but pathological narcissists are narcissistic to the point that they cannot have normal human relationships, ever. Again - you're not going to fix someone like that with a training course, because it's more of a embedded psychological and emotional disability. Even therapists don't rate the chances of improvement very highly after extended sessions - so a week or two certainly won't be enough.
None of this has any connection to being anxious about something, like a deadline, or a date, or an exam. Or with panic attacks. Or with being an overtly anxious person who may be prone to worry. That's a different syndrome and isn't noticeably linked to abusive behaviour.
Instead, these are classed as personality disorders - so not quite mental illness, but also not quite sanity.
There are no psychotic delusions, and no loss of lucidity. But there are severe emotional distortions and disabilities which can be contagious in that they promote harm of self and others. They're also just plain unpleasant and toxic to be around.
Trying to decide if someone with one of these conditions is actually responsible for their own actions is as much of a philosophical problem as a moral one. But it's absolutely clear that people with Dark Triad issues are almost invariably poisonous in organisations and will create extremely unpleasant and toxic experiences in a work environment.