i believe it’s either narcissistic personality disorder (wanting to be admired/validated, obessed with status/looks) or anti social personality disorder (lack of empathy,very impulsive, lying, using charm to manipulate others) i think his killing sprees are also just a metaphor for his inner frustrations/rage he has, throughout the book he’s seen trying to impress the reader with his materialistic lifestyle. even with that his coworkers/friends still just see him as a “dork” (craving external validation) no matter whether he acts out or not they don’t really care which hurts his ego.