In Catch-22, Dunbar would routinely cultivate boredom in an effort to extend his life. Why did he consider that worthwhile? Why did he want a long but boring life?
One possible answer is that he simply doesn't think about that - that's part of the irony. He doesn't know exactly why he wants to live for a long time, just that he does, and that intentional boredom is (supposedly) one way to do that. The author is deliberately causing the character to behave in an absurd manner. A major theme in the text is the characters' regular lack of reflection on the reason for their behavior.
Occasionally the characters will even realize how absurd their behavior and/or situation is.
A few random examples - Major Major gets promoted to a major by chance due to his name. Colonel Cathcart promotes him to Squadron Commander to solve a headcount problem, informing him that it doesn't actually mean anything. Major Major keeps getting the same papers back for him to sign until he signs "Washington Irving" on them (which were largely pointless to begin with), at which point they stop coming back.
There are hundreds examples in the book of bureaucratic absurdity, and absurd behavior from various characters.
TL;DR The character just doesn't think about why he's doing it. It's supposed to be ridiculous behavior.