Quote 1
"They were no match at all for a hunter with his wits about him, and a high-powered rifle. I was bitterly disappointed.” (1.90)
Okay, let’s take a look at this. How could the animal compete against someone with wits and a high-powered rifle? Zaroff never pauses to consider that the hunt is a terribly uneven playing field.
Quote 2
"Simply this: hunting had ceased to be what you call `a sporting proposition.' It had become too easy. I always got my quarry. Always. There is no greater bore than perfection." (1.96)
To Zaroff, hunting is no longer a sport when the animal becomes too easy to kill. Hey—here’s an idea: try fighting without the gun and see how far human reason will get you in the face of animal instinct.
Quote 3
"Oh," said the general, "it supplies me with the most exciting hunting in the world. No other hunting compares with it for an instant. Every day I hunt, and I never grow bored now, for I have a quarry with which I can match my wits." (1.105)
Clearly Zaroff has an issue with being bored. He believes that humans are equal competitors, but he’s lying to himself if he doesn’t factor in that he knows every inch of the island and that those poor suckers don’t even know where Death Swamp is located.