Time changes. Just like most people on here are into the modified scene of the 60's-80's, there were people who were into the midget scene of the 40's and 50's. Midget's popularity died and turned into modified popularity.
Time changes. Baseball isn't as popular as it once was. Lacrosse and soccer didn't exist in much form at all in the US in the 1960's and 70's and now both are very popular at the local and in the case of soccer, national level.
Time changes. Technology has been a boom for certain sports. The betting angle has made certain sports more popular than ever. Try getting a ticket to a SEC football game. Try gettting an Eagles/Cowboys ticket for a fair price. People go and post, talk and use their devices while at the game. Instead we have racetracks putting up signs telling people NOT to use social media. Football figured it out, racing management said no.
Time changes. As recently as 2013 I spent tens of thousands of dollars on my sprint car operation and attended probably 30 races that year. In 2018 I went to three races, spent less than $100 doing that, and instead spent about $15,000 in competitive trapshooting. I still look on social media to see how my friends did and for some good races, but that's it.
Racing isn't coming back to what it was even 10 years ago. Enjoy what is left, which is significant if you look around and are willing to travel a bit. Lots of good action out there.