Successful societies become bloated. It is not that they become weak, but that so many weak people appear that a market for delusion is created.
Their wealth is not the cause of their problems, but it allows the weak to survive and prosper, just like technology does.
In other words, we see two models of civilization:
One optimizes production and dies by bloating; the other optimizes control and dies by fighting over control. Obviously the former triumphed with the rise of the West, but it remains to be seen if it can resist the many attempts to dominate it, including most likely from within, since that is what took down the Greek and Roman states as well as Aethelred II.
We might call these models “supply-based” and “demand-based.” Supply-based systems seek to increase production, creativity, and invention, even if these are not equally distributed and therefore a hierarchy of wealth, power, and status emerges; demand-based societies aim to give things to their citizens in order to enforce unity, and therefore need more tax targets. The West has always been supply-based, at least until the most recent conquest, and the rest of the world especially the third world appears to be demand-based.
Our political shift toward egalitarianism, starting with the French Revolution but accelerating after WW2, changed us from a supply-based organic society to a demand-based modern state run for the perpetuity of government, not the perpetuity of the civilization or its best citizens.