Or you've already been said person, in which case it won't harm you anymore. Not to mention that it's inevitable that you will hurt the victim because it already happened from the victim's POV, who you've already been. The egg is in a fundamentally contradictory realm anyway because it's asserting free will and same-universe time travel at the same time.
> the story's premise kinda eliminates our usual ideas about morality
Allowing for psycho maxxing, yes. You can take "I should be a good person" from it, but so far you haven't made a compelling case. There's no reason why you shouldn't be an exploiter in 1-10% of your lives, living off the direct and indirect suffering of the 90%. Kind of like within a modern life you can choose to suffer 90% of the time (work, gym, studying,...) to get a halfway decent 10%.