Well, as a lifelong sports fan, I disagree strongly with your statement. I don't give a damn about NASCAR, basketball, or hockey, and there is a limited overlap between MLB and the NFL. People do, on the average, separate the sports into their own compartments.
Let me ask you:
I assume that you craft a budget for your family's expenses. So when you craft your budget, do you have a category for "entertainment," or do you have a category for each individual entertainment expense: MLB, minor league baseball, NFL, NBA, Broadway shows, movies, DVDs, CDs, etc?
I'd be willing to bet that you, and the vast majority of people, budget according to one large category: entertainment. Whether or not you like NASCAR or basketball or hockey is precisely my point: MLB and NASCAR and the NBA and everything else are all competing for that little slice of pie in your budget that is labeled "entertainment." The fact that you choose MLB over NASCAR doesn't mean that other people don't choose NASCAR over MLB.
I think your perception of how people spend their money is incorrect. Maybe people break sports into their own compartments when talking about likes and dislikes, but I bet very few go so far as to compartmentalize them when it comes to their spending habits. In fact, I'd bet that the only people who would do such a thing are people who have season tickets--and even then, I bet they only break out the cost of the tickets themselves, with any ancillary expenses falling into the "entertainment" section.