Why did the Roman government have large expense?

The Roman government did have large expenses because they had to pay for the maintenance of the army. Thus the major need of army was to maintain slaves.

Explanation:

Slavery is a reason for the drop of the Roman Empire because the wealthy who hire duties pay less to the slaves for agriculture then the farmers and the wealthy make gain while the farmers became jobless. The goverment created the wealth it spent by charging the poor it built by pushing surmounting and compelling entire tribes of people's and then setting them to serve essentially in the iron, copper, tin, silver and gold mines scattered regarding the Roman's newly established colonial territories so as Spain.