Excessive military spending

                  Excessive Military Spending

from Wikipedia

 Excessive military spending led to the fall of the Roman Empire because the cost of the military was a constant drain on the empire and left few spending resources. There was a lack of Roman men in the army, so most of the troops were made of foreign, hired soldiers that were untrustworthy, unreliable, and expensive. The cost of the soldiers and other necessities caused taxes to be raised often. This weak and costly army helped cause the  end of the Rome.