Fall of Rome in a nutshell:

Rome conquers much of its enemies from 300 BCE-140 BCE. The wealth of these conquests go mostly to the warrior class in a society where you need to be a land-owner to serve in the military and participate in said conquests and collect spoils.

The economic inequality that results from the unequal distribution of conquest loot elevates the position of the "tribune of the plebes"--a district-level political position with out-sized veto power that gives the people control over the senate in some aspects. The Gracci Brothers--AOCs and Bernie Sanders' of their time--begin demanding more money for the renting class from the asset-holding class. The asset class doesn't much like this, so they assassinate the Gracci Brothers, which injects political violence into the wealth inequality fight. Political gangs begin to emerge.

Gaius Marius--a popular Roman consul and general--reforms the military to allow military service for non-land-owning Romans, as they will gain their new lands upon conquest (a short-sighted solution to the "not-enough-soldiers" problem). This essentially makes soldiers loyal to their generals as voters because the better campaigns their general got, the better the lands and spoils of their battles would be. Men went to war simply to elevate financial and political status in a society where that was increasingly difficult. Thus began the era of clientelism from both sides.

Political gangs and lawyers become increasingly important in politics for both physical and legal protection from the opposing party. As bloodshed increases, senators are eventually killed on the floor of the senate (bludgeoned to death with the tiles of the senate roof) when fighting between Saturninus' gangs and Marius' gangs spills into the upper-class and kills both of them. Pompei and Julius Caeser and Cratius get rich and rise to power in the background of this conflict, and step in to fill their successor's shoes as the most powerful generals and senators in short order.

Eventually the pact between Caesar, Pompei, and Cratius for power-sharing breaks down when Caesar's daughter--married to Pompei--dies, and thus severs blood ties between competitive political elites. They go to war with each other, and they take their base with them. Rome rapidly dissolves into anocracy and ceases to function as a Republic from that point forward. Pompei and Caesar are both killed.

The whole chain is set in motion with wealth inequality and economic and political winners trying to hold onto power, and taking the Republic down with them when they cannot. Sound familiar?