Where is this incessant déjà vu coming from?
And why do I see Caligula, Tiberius, Livia, Nero, and Commodus every time I turn on the TV set?
And why do I suddenly understand Roman decadence so clearly? in all its frustration and horror? its incredibility suddenly credible?
And why do the words of William Faulkner (Absalom! Absalon!), Ovid, Gibbon, and Robert Graves keep ringing in my ears?
And why do I have this unsettling feeling that you're whistling in the dark?
I knew you were going to say that ...
It should be pointed out that all of these people lived in the 1st century BC or AD except Commodus, and he was murdered in 192.
The height of the Empire is usually considered to be the 2nd century, though the Golden Age ended when Commodus came to the throne.
IOW, the decadence we associate with the fall of Rome mostly took place prior to its Golden Age and centuries before its Fall. (Whenever you date that.)
This is largely because we have fascinating historical records from this early period which are missing from most of the later days of the Empire. It's entirely likely there were equally interesting and evil characters in the 300s and 400s, but we have little information about them.