Seems like every system that achieves apparent stability but with a stable trend in only one direction will eventually reach a cathartic overturn. Population growth under absolute resource constraints, that interlocking network of pacts prior to ww1 that for a while looked like a mechanism for peace. And wealth concentration? What you need for stability beyond that horizon is some form of control valve.

I've recently started diving into the "what if" of a hypothetical society that used some kind of "financial lynchmob ritual" as an institutionalised check to infinite wealth concentration: it would be limited in rate, e.g. one property nullification per year per 100 million inhabitants. It would be open nomination, secret vote, "winner" would get stripped of every property and contract, perhaps with some generous lifetime pension in return. It would basically be like an inverse bankruptcy, just concentrated on one creditor instead of one debtor. The rate-limit would make sure that it wouldn't devolve into an ever accelerating tall poppy hunt, but it would be enough to force a requirement to be not disliked too much on the 0.0001% rich. This could have massive benefits, way beyond the direct spoils of occasionally nationalizing some Oracle or Facebook or Aliex. What would be its unavoidable failure modes? Lots of mud-slinging between the super wealthy, that wouldn't be pretty. Lots of defecting into other countries, for sure, but let's assume some total hegemony for the sake of the mind experiment. Seclusion, most rich and powerful would be more invisible than they already are. Chances are you'd eventually have a caste of super rich that keep an extremely low profile. Perhaps even secretly pulling strings for some exceptionally visible and unlikeable dickheads to somehow stumble into wealth, as a caste of sacrificial decoy rich. And the success of those, until eventually stripped, would make others try to emulate them. Perhaps that would be the failure mode?