It isn't enough that the bad guy is prevented from doing his bad deeds; he must suffer as much as possible. It is as if the existence of evil - or something that can be designated as evil - provides a safe haven for the good to engage in evil. It's a safe space to indulge in inflicting harm, to experience the sublime of suffering.
M.E. Thomas, Confessions of a Sociopath: A Life Spent Hiding in Plain Sight
bad-guy, good-and-evil, good-guy, hypocrisy, inflicting-injury, suffering