I don't understand how you can be uncertain between 10 and 1000 but not 1 and 10 or 1.1 and 10, especially in the face of things like empathy, symmetry arguments, reductionist personal identity, causal and acausal cooperation (not an intrinsic value, but may prescribe the same actions).

Self-preservation and lots of other self-centered behaviors are real psychological adaptations, which make indifference between self and random other very unlikely, so I draw a tentative lower bound at the factor of 10. Empathy extends fairness to other people, offering them control proportional to what's available to me and not just what they can get hold of themselves, but it doesn't suggest equal parts for all, let alone equal to what's reserved for my own preference. Symmetry arguments live at the more simplistic levels of analysis and don't apply. What about personal identity? What do you mean by "prescribing the same action" based on cooperation, when the question was about choice of own vs. others' lives? I don't see a situation where cooperation would make the factor visibly closer to equal.

I also don't understand the point of preaching egoism; how does it help either you personally or everyone else?

I'm not "preaching egoism", I'm being honest about what I believe human preference to be, and any given person's preference in particular, and so I'm raising an issue with what I believe to be an error about this. Of course, it's hypothetically in my interest to fool other people into believing they should be as altruistic as possible, in order to benefit from them, but it's not my game here. Preference is not for grabs.

Finally, 10 and 1000 are both small relative to astronomical waste.

I don't see this argument. Why is astronomical waste relevant? Preference stems from evolutionary godshatter, so I'd expect something on the order of tribe-sized (taking into account that you are talking about random strangers and not close friends/relatives).