If the people don't like the dictator, it's entirely in their power to remove the dictator. How exactly can one person stay in power over an entire nation of millions? It's only because the people there tolerate it.
If the society needs a lifespan limit to limit the damage dictators can do, the problem isn't the lifespan.
Or they're too poor to leave for greener pastures. Dictators are in power not because their people tolerate them, but because they don't have a choice in many cases. There's exceptions, but generally the stigmatized term "banana republic" aptly describes many of these places dictators control for a reason.
They absolutely do: they can rise up and revolt. How is a dictator going to stop them? He's one person. How exactly does one person stay in power over millions? No dictator in history has ever been a Marvel-comics-style supervillain with fantastical powers. Dictators stay in power because their people tolerate them.