Final answer:
The narrator exploits Fortunato's excessive pride in his wine expertise by luring him into the catacombs to authenticate a supposed pipe of Amontillado, leading to his doom.
Step-by-step explanation:
The narrator takes advantage of Fortunato's excessive pride in his knowledge of wine. Recognizing Fortunato's vanity and his desire to assert his superior discrimination in matters of wine, the narrator lures him into the catacombs on the pretense of verifying the authenticity of a pipe of Amontillado.
The narrator flatters Fortunato's ego by appealing to his self-proclaimed expertise and devalues the opinion of Luchesi, another wine connoisseur, making it irresistible for Fortunato to resist proving his discernment. This exploitation of pride is the bait that ultimately leads to Fortunato's tragic fate.