I actually found some great demographic info (age, race/ethnicity, gender, income) for the Nielsen viewership of the NBA, MLB, NHL, NASCAR, golf, college football bowls, NCAA Tournament and MLS here:
https://www.theatlantic.com/business/arc...ns/283626/
It's data from 2012-13, but the age 2-17 and age 18-34 ranges from that time are pretty close to tracking with the Generation Z and Millennial generations, respectively. You can see where the interest from young people back then are now translating into a different sports pecking order today.
It essentially backs up my anecdotal observation: at that time, only 14% of NASCAR viewers were under the age of 34 (which effectively constitutes today's under 40 crowd), which was the lowest of any of the sports that they evaluated with the exception of golf at 12%. In contrast, 45% of NBA viewers at the time were under the age of 34 (and that's coming from a much higher number of sheer viewers), which is why I've long said that if I was a multi-billionaire, the best long-term pro sports investment out there is to buy an NBA team. Even MLB was at 24% of their viewers being under the age of 34 at the time.
Meanwhile, NASCAR also had the lowest percentage of over $100,000 income viewers of the sports that they evaluated at 14%. In contrast, golf had 27% of its viewers with over $100,000 in income. Interestingly, the NHL actually had the highest percentage of six figure income viewers at 33%.
Essentially, NASCAR didn't attract younger members of the Millennials and Generation Z back then, which means they're much more unlikely to be watching NASCAR today when they now are starting or in the middle of their careers earning higher incomes. Meanwhile, NASCAR is the worst of the sports evaluated at attracting higher income viewers.
There isn't a more toxic combo to TV executives than old low income viewers. They worship young high income viewers (and pay massive premiums to reach those specific people) and can tolerate old high income viewers and young low income viewers... but there's no upside at all to concentrate on old low income viewers. Looking at that data, it's not a shock that mainstream outlets are spending less of their capital (both time and money) on NASCAR compared to other sports.
To be sure, there's still value to NASCAR as a live event along with historically strong branding and advertising tie-ins that go beyond other sports (where ads on cars and uniforms are unabashedly front and center), but it is going from what was a close-to-mainstream sport in the early-2000s to a more niche sport like boxing or its Indy Car counterparts.