Rome's territory was sacked by "barbarians", nevermind the pilfering and stealing other "Romans" did. Consider that when emperors died, the usual course was to

Rome's territory was sacked by "barbarians", nevermind the pilfering and stealing other "Romans" did. Consider that when emperors died, the usual course was to murder their whole family and sack their belongings, all for good measure. It was not a stable thing to be at the top in Roman society, you gained a target on your back due to your wealth and power in an inherently violent society. Combine all this with looting over the centuries, and what's left to us is a lot less than originally existed.