The fall of Rome was caused by many reasons building up overtime but the main ones were the political corruption and all the land they had.
One of the reasons political corruption arose is because more men were needed for the military so people who weren't citizens were being recruited. These people weren’t loyal to the empire so they went against it most of the time causing a lot of corruption within the empire's borders. The vast amount of land rome conquered also played a huge role in the fall of Rome because there was so much land the government couldn't watch over it all at the same