If I tell you “I’m torturing an animal in my apartment,” do you go “well, if there are no other animals being tortured anywhere in the world, then that’s really terrible! But there are some, so it’s probably not as terrible. Let me go check how many animals are being tortured.”
(a minute later)
“Oh, like ten billion. In that case you’re not doing anything morally bad, carry on.”
I can’t see why a person’s suffering would be less morally significant depending on how many other people are suffering. And as a general principle, arbitrarily bounding variables because you’re distressed by their behavior at the limits seems risky.
Quoting Kelsey Piper: