The principle discussed in the snip highlights the story of General David Petraeus, a highly disciplined military figure who ended up having an affair with his book's author. This led to the realization that even the most disciplined individuals can succumb to situations, emphasizing the importance of environment over willpower. The insight suggests that placing oneself in certain environments can make it more likely for undesirable events to occur, and that environment matters more than willpower. The example from the military challenges the perception of military personnel as paragons of willpower and grit.