More like an internal decay. Like a tooth rotting from the inside out. Bigger or smaller makes little difference - it’s the internal dysfunction which drives it until a crushing, agonizing collapse.

A lot of issues are involved. Government instability and lack of legitimacy. Economic decline and irrational economic behavior. Hardening of a corrupt plutocracy into an intransigent aristocracy with independent power bases. Detachment of the population from the core civic identity of the state. Immense incompetence and nepotism in a period of increasingly centralized and bureaucratic control over society. It goes on and on.