We can see a similar grand historical pattern repeated throughout history across pretty much all hegemons, empires, and societies of a complexity above that of a subsistence hunter/gather tribe. There is a tension between the central ruler, whether that ruler is a king or senate or whatever, and the oligarchs/rich. Sometimes the oligarchs themselves are part of the ruling body such as in the Roman Republic. The central ruler wants to centralize power in order to more efficiently wield it such as against outside threats or to deal with disasters, and to eliminate potential other threats or centers of power that might result in rebellion. The oligarchs even if they do not necessarily want to rebel, try to get more wealth which in ancient times often meant land. This push-pull dynamic and struggle is played out over generations but what has invariably happened is the oligarchs have gradually eroded the wealth and power of the central government as they get granted concessions, favors, or tax exemptions. The ruler often ends up granting these concessions in order to secure the loyalty of that generation of oligarchs or because these became in some way related to the ruler, such as by marriage or association. However once granted, these privileges are hard to claw back in their entirety, even though individual oligarchs or nobles might have their wealth confiscated in occasional crackdowns. This leads to a gradual hollowing out of the power of the central government as it gets starved of resources and eventually falls to either internal or outside pressures. The oligarchs end up doing this through trying to maximize their individual wealth and power even though it serves none of their interests to see their society fall, as often the result of a new society/dynasty is the confiscation of much of the wealth and breakup of the old existing status quo.
We see this in the cycle of the Imperial Chinese dynasties as often the first stages of the decline and fall of a dynasty would be the erosion of the dynasty's budget and tax base even if the overall economy was doing well. We see this in what happened with the US after about the 1970's but accelerating in the 1980's under Reagan and the increasing financialization of the United States economy, which allows the pooling of wealth into the financial institutions that then engage in regulatory capture which prevents significant reversion to the previous status quo.