Emphasis on the some, as I know all too well the old tale of no one not enjoying [subject] more than fans of [subject]. Also to be really clear, this isn’t intended as a dig at those that don’t become jaded, so much as genuine curiosity.
I’ve had the misfortune of really enjoying some genre stories only to find it harder to maintain interest in others I come across due to overfamiliarity making what might otherwise be interesting twists or turns feel a little…Predictable. It’s a bummer that even taking breaks from some genres doesn’t seem to assuage.
Perhaps this makes me a shitty fan*, but I simply avoid the genre for a while, or reread/rewatch works that I know to be good, divergent, or atypical. Then when I come back it feels fresh again.
*in my case it’s fantasy anime and manga. Specially isekai. And ooh boy those can be cookie-cutter repetitive.