What would be achieved by being done? If Sysifos finally managed to ballance that rock on the top of the hill, and could walk away. What would be his purpose?? Would we still talk about him?
The universal truth about him lives because of its simplicity. Rolling a boulder upp a hill; forever. We can alla interpret it like we please. I´ve had jobs that feel like that. It can be seen as OCD. And so on, and on. Being that symbol, is his purpose. Are we searching for these truths in every story we hear? Gossip doesn´t need to be true, it needs to be a good story.
Some people mistake this need for story, with actually caring about the characters. There is no caring for fictional characters, some of them are there to die! This has terrible efects when famous people  are hounded, the audience doesn´t care, and that is the real tragedy.