To derive a sense of sadistic pleasure.
Research has indicated that those on the more malignant end of narcissism tend to derive joy from seeing sad faces. This is not news to anyone who has been a survivor of a narcissist, a sociopath or a psychopath. They enjoy inflicting pain – to be the cause of it is even more thrilling for them. Sabotage enables them to see their sick and twisted mind games unraveling in real time on the stage of the victim’s life come undone.