The players change, the grudge does not
Ask a fan why they hate a particular rival and the answer is often a story about a game neither the fan nor most of the current roster actually witnessed. The specific players who created a rivalry's original grievance are frequently retired, sometimes for decades, by the time the fixture is treated as the most important night on the calendar.
That should be strange, and I think it is worth sitting with the strangeness rather than explaining it away. A rivalry, once it exists, seems to detach almost entirely from the particular humans who caused it and start renewing itself on its own terms.
Inherited stories, not remembered ones
What actually gets passed down is a story: this team disrespected us in this way, this fixture matters more than the standings say it should. A new fan absorbs that story from the fans around them long before they have any personal experience to weigh it against, and by the time they do have personal experience, it mostly just confirms what they were already told to feel.
This is not a criticism. It is closer to how most inherited loyalties work, in sport and outside it, and pretending a rivalry is sustained purely by lived memory ignores how much of its energy is simply passed hand to hand.
Why it still needs real stakes sometimes
A rivalry sustained entirely by inherited feeling and no actual consequence eventually curdles into theatre, which is why the fixtures that matter most tend to be the ones where an old rivalry and genuine playoff stakes line up in the same week. The manufactured intensity needs the occasional real one to stay honest.
When that alignment happens, you get the nights that create the next generation's inherited story, and the whole cycle restarts with players who, thirty years from now, most fans in the building will never have watched play a single shift.