Final answer:
Zaroff is defeated by his own hubris or overconfidence.
Step-by-step explanation:
In addition to being defeated by Rainsford's hunting skills, Zaroff is also defeated by his own hubris or overconfidence. This is demonstrated when Zaroff underestimates Rainsford's abilities and becomes complacent in his own game. As a result, he fails to anticipate Rainsford's clever strategy and ultimately falls victim to his own arrogance.