Imagine a generation spaceship, flying through the cosmos with little recollection of the original world and no destination in sight. Of course on this ship, there will be those in charge of ruling the ship and those that are not. This ship is heavily reliant on drones and other machines, so only specialized jobs exist for people.
What can cause the non-ruling class to revolt against those in charge?
I considered a division of wealth could be a cause, but I remember watching a movie about a train that houses all of humanity, where the front of the train is prosperous and the back eats roaches. I'd rather not have too similar of a concept.
Maybe the ruling class treats the lower class as slaves and servants? This too seems like a common theme in dystopian stories like these.
Basically, I am trying to think of a non-cliche theme that would cause a lower class to revolt against its rulers.