You're given the option to torture everyone in the universe, or inflict a dust speck on everyone in the universe. Either you are the only one in the universe, or there are 3^^^3 perfect copies of you (far enough apart that you will never meet.) In the latter case, all copies of you are chosen, and all make the same choice. (Edit: if they choose specks, each person gets one dust speck. This was not meant to be ambiguous.)
As it happens, a perfect and truthful predictor has declared that you will choose torture iff you are alone.
What do you do?
How does your answer change if the predictor made the copies of you conditional on their prediction?
How does your answer change if, in addition to that, you're told you are the original?
3^^^3 dust specks in everybody's eye?
So basically we're talking about turning all sentient life into black holes, or torturing everybody?
I mean, it depends on how good the torture we're talking about is, and how long it will last. If it's permanent and unchanging, eventually people will get used to it/evolve past it and move on. If it's short-term, eventually people will get past it. So in either of those cases, torture is the obvious choice.
If, on the other hand, it's permanent and adaptive such that all life is completely and totally miserable for perpetuity, and there is nothing remotely good about living, oblivion seems the obvious choice.