Rome started as a republic, then turned into an empire. An empire that inevitably collapsed, as all empires have. Always have. Always will.
Better try your best to revert to that republic thing... if you still can, and if you can keep it... Europeans think a hundred miles is a long way. Americans think a hundred years is a long time.
Roman culture wasn't a true republic so much as a patriarchy, and personal notions of family honour and ambition drove a four hundred year imperial expansion spree. Rome was never likely to remain stable because sons always had to outdo their fathers to increase the family's glory and social standing. The roots of that were already present long before the generation of Pompey, Crassus and Caesar.
Stability won't be possible as long as the aim of every true aristocrat is honour in battle and the limitless accumulation of personal wealth. It doesn't matter what the official title of a political system is - if it has an aristocratic caste, then war and empire are inevitable, for as long as the rest of the population and the available resources can support them.
... if it has an aristocratic caste, then war and empire are inevitable ...
If so, can we count on any kind of epiphany within their class soon which will bring about their voluntary ... goneness? The music's over. I've turned out the lights. Bye Bye.
On the rest, yes, I agree with you. Most economists teach a theoretical framework that has been shown to be fundamentally useless. -- James K. Galbraith
The empire can really be seen to crumble in either 337AD with the split into east and west, or 376AD when Valens allowed the Visigoths to settle.
That isn't 4 centuries Life should consist in at least fifty percent pure waste of time, and the rest doing what you please.
This meant they didn't have access to the full Rome-based military and political machine. After the start of empire the emperor had a monopoly on that - which did make it less effective and less flexible.
Effectively if you wanted the top job you got it by taking down the emperor, and not by winning new territory. So the emperor became enemy number one, and energy that could have been spent on expansion was either diverted to internal wars of succession or monopolised by emperors who were trying to maintain their position.
And of course it depends how we define "stable". Civilization of the western Mediterranean changed as much between -100 and 100 as it changed between 300 and 500... Auferre, trucidare, rapere, falsis nominibus imperium; atque, ubi solitudinem faciunt, pacem appellant.
