Just because you can "vote" for candidates that make rules on your behalf does not magically make the tyranny non-existent. It just makes it more difficult to dispose of the tyrannical system because it does not simply come down to taking down a single ruler.
In the US, even if Joe Biden were to croak tomorrow, it would not change one thing. That is because he is not the problem, the whole government infrastructure is, as those who are pulling the strings can hide quite easily in the shadows.
Having a singular ruler with all the power means that there is a single point of failure. His rule will either be great or terrible based on his actions alone.
But what can be done when the problem is entrenched among many different groups and individuals? You are dealing with many heads of the hydra, unable to solve anything politically with the vote (which can and has often been stolen).
And to make matters worse, many in power are unelected and not even check by the fake voting anyways.