The Roman Empire was known to support pleasures of the body through prostitution and violence. Roman Emperors Caligula and Nero allowed tens of thousands of prostitutes to occupy Rome without punishment. These emperors were well known for having lavish parties where guests were allowed to eat and drink until they were sick and engage in orgies. At the Colosseum, gladiators fought for sport and the poor were brought in to fight and die by lion attacks for no other reason than so the crowds could enjoy watching their deaths.
Unlike in a democracy where the public votes its leaders into office, Rome never created a public system for deciding how emperors would be selected. The system in place consisted of the emperor, the Senate and the emperor's army, known as the Praetorian Guard. The military often chose the new emperor based upon the wishes of the current one. Eventually, each throne was sold to the highest bidder, regardless of his ability to lead. This led to weakness in leadership and support from citizens, leading to an overall distrust of government.
At first the empire had an army to be feared. Then the so-called barbarians from the countryside, who would be considered today's revolutionaries, began to attack Rome with constant attempts to overthrow it. The cost of maintaining an army to fight these constant battles left Rome in more of a war state than a social state. Citizens were being taxed not to protect themselves but to protect the corrupt emperors and wealthy politicians, who were hardly taxed at all.
With increased taxes to support wars to protect Rome and its corrupt line of emperors, the civilian masses were unable to survive. They could no longer afford to live in Rome and started to leave the empire state to find cheaper living. As most of the military was now being used to defend the emperor, it no longer conquered new lands, in effect stealing and bringing goods and gold back to the state. Gold, however scarce, was still being used. The value of coins once filled with gold decreased, and civilians could not pay the cost of items whose prices were raised because of low supply. This was a perfect storm of inflation and decreased market value.
The final blow to the Roman Empire came when the civilian population had decreased so much that much of what remained in the city were the remaining military, politicians and the emperor. The military was charged with protecting the emperor, but it was no longer regularly paid to do so. It too began to leave the city. The term "the emperor has no clothes" is important here. An emperor with no one to lead, no one to carry out his political wishes and no one to protect him is surely an empty emperor. The fall was complete.