You probably learned Roman history from a Marxist, so you think the Republic fell due to class warfare.
Partially true, but you probably weren’t taught that the primary grievance of the poor was their large-scale ethnic replacement, coordinated by the rich.
Every Roman writer mentions this, but modern historians minimize it. However, DNA analysis has now proved it beyond a doubt:
In a 2019 Science study, only 2 out of 48 samples (4%) taken from Rome during the Imperial Era cluster with Western European populations, compared with 8 out of 11 samples (73%) during the Republican Era.
By the time the Republic fell, there was hardly a Roman left in Rome.