well according to http://www.reallycoolblog.com/ "As the good qualities which had kept the stability of the commonwealth intact accordingly disappeared, Romans began to violently turn against each other in their pursuit of more wealth".
also from the same source it states that “When toil is replaced by an attack of indolence, and self-control and fairness by one of lust and haughtiness, there is a change in fortune as well as in morals and behavior". This meaning that money and power can cause people cause people to become corrupt.
:)