Kelly Ellard got an 11 guilty to 1 innocent jury in one of her multiple (4?) trials because a juror could not believe that Ellard had lied under oath. The Juror even asked the Judge to confirm that was not possible, and was told that she had to form her own opinion.

A criminologist tells of being asked "why do people steal" by a church lady type after a public lecture. His response was "criminals wonder why you don't steal". Sometimes they think they will get away with it. In other cases the thrill of getting away without any consequence is part of the motivation.