Quintillionaires of the future may pay for elaborate escape rooms wherein the entire universe is simulated. I still think if this is all just a simulation, it's some type of archeological study.
Seems the most obvious reason for a simulation would be to check the outcome from a series of different conditions. Eg what would have happened if humanity had done X? Was that pivot important? So we could just be someone’s history homework.
The accuracy of the simulation's predictive power of course depends on whether or not you are simulating the universe exactly. But I do wonder if there are some simplifications you can make. Say, you only simulate our solar system down to the quantum level, but simulate the light from outside our solar system based on past observation, at a macro scale.
Of course, the accuracy may also depend on whether or not "God plays dice with the universe"; if quantum effects are truly random, and can affect things that happen at a macro scale, then this future-viewing might not really work.