“You should have planned ahead for this sort of thing”

Yes. Marked by opulence and a distracted upper class, depending on foreign born nationals and the impoverished to defend them from the mob. A military class they eventually spit on and denied access to anything “Roman” which wasn’t a great incentive for you know, defending them from their own disgruntled citizens or enemies at their door. They cared more about their money and orgies and pedophelia than they did at maintaining the cogs of Empire of which their lifestyle depended. Bread and circuses and a whole lot of arrogant prejudice.