Most fans of anything are... at best... "casual fans". It's just the nature of sport-as-entertainment. I don't hate on that, but I do realize it.

I'd be willing to bet that 80+% of the people who are actually going to shell out the $100 to buy this PPV "boxing match" probably don't even realize there are undercard matches they can watch. That they are paying to watch. They are only interested in getting together with their buddies for the spectacle!

It's probably very similar, if not less-so, in the world of MMA fans who buy or watch PPV events. They likely have no real clue about the undercard fighters or any genuine desire to watch them. They just want to see "the main", and spend time socializing and getting drunk until it starts.

Real, educated, dedicated, knowledgeable fans of anything, are rare. Most just own the apparel.