Good question. There are four broad categories for reasons why staff will conduct fraud and theft.
4. Opportunity. Plain and simple.
Research has shown that 25% of employees are totally honest, 25% are totally dishonest and the remaining 50% are swayed by opportunity. If theft is perceived or proven to be risk free, a high proportion of staff will take advantage. This is particularly true if they witness or suspect other members of staff of getting away with it. Why hold out when others are profiting?
Allowing stealing to be easy or unchecked has two major drivers. Firstly, encouraging more people to participate. Secondly, allowing each thief to be more efficient and steal more from you.