Before Caesar, Rome actually had checks and balances to keep one person from amassing too much influence. For example, they had two consuls, which was the highest political position at the time and acted like as the heads of state.
Until Caesar fucked up those systems by literally declaring himself “dictator for life”. So really, it’s not always been this way, it’s usually just a few individuals that keep fucking it up for everyone else. Until they end up with a knife in their back.