Could you explain how this holds for monarchies? The succession of power was mostly based on blood relations and frequently brought along major changes to existing power dynamics. Meanwhile the majority of the population was barred from gaining any real economical or political power, aside from very few cases.

As far as I can see, greed isn't automatically the biggest determining factor in such systems. It can be, but I'd need to read convincing studies by historians to believe you on this.

(of course I'm not advocating for monarchy)