During the Pax Romana the romans were very strong at the time. You might think, then what caused the Roman empire to fall. Well there are many reasons why, but what did money have to do with it? The Romans could have used the money they had in a different way for them not to fall.
To keep the army to defend Rome from attacks cost a lot of money. This was a constant drain to the government. Spending on the army left a little amount of resources for other things that they needed. Mostly like roads, and providing public housing(Rome). One thing that the empire did is they started to higher foreign soldiers, the foreign soldiers did not follow orders as well as the regular soldiers(Roman).