ABSTRACT
This chapter explores how insider behaviour develops within an individual through interactions between internal factors, such as personality and experience, and external factors, such as work environment, relationships, and external threat actors. Most people are not, and never will be, an active insider, but exposure to a combination of internal and external factors can put them on the path to becoming one. Chance and opportunity play significant roles in the development of insider behaviour, as do personality traits such as psychopathy, narcissism, and Machiavellianism.
