We all have a different perspective. If I hadn't discovered wing cars - real miniature racing cars - I'd have quit slot cars long ago. Yes, when I was a teen in the 60's racing a model of my favorite 1:1 race car was appealing, but that lost appeal as I became an adult. I now find these "scale" (actually only "scale appearing") slot cars boring. I want to play with maximum performance miniature race cars.
Many kids in the 60's had their own sources of spending money. Their parents generally didn't care if they biked or walked across town without adult supervision as long as they were home for dinner. Today, it's very unlikely parents will allow the child to go so much as the next block away without adult supervision. It's a very small segment of today's population that even has a raceway in the same city let alone somewhere close enough that a kid might go on their own. Today, most of the kids I'm familiar with are completely dependent on parents/adults for both money to spend on a hobby and vital transportation for something like slot cars. Catering to kids almost always fails - the hobby needs to cater to the parents of kids. Most of the slot car enthusiast kids I know have a slot car enthusiast parent (from the 90's boom cycle) or grandparent. Parents not interested, kids not either.
Another factor I see is that slot cars appear very low-tech, especially compared to radio-control models and digital-controlled model trains. I believe if the raceset makers hadn't gone "digital" slot car sets would be dead now, only a past memory for the older of us. I'm familiar with slot car raceways which are or have been located in shopping malls. The kids come by and look at me zipping around the track, and the impression is any moron can do that, the cars are stuck to the track. They move on looking for a more challenging experience. There are plenty of them, too, at least ones that seem to be a lot more challenging. A few will give it a try, though, and quickly discover there's a lot more challenge than meets the eye. To go zipping around like they've seen me do takes some skill. Unfortunately, the challenge wanes quickly, and when the kids can't master in less than 15 minutes, they give up - too hard. That video game on their smartphone is a lot easier - costs less, too. Parents probably gave them the phone and all of the entertainment apps on it, so they can play free almost forever. When they wear it out, or the tech and sparkle advances every 6 months or so, parents will provide them a new one. Then for some parents, $20 for 15 minutes of entertainment seems too expensive. Yes, the theme park costs a lot more, but it's an all-day adventure that totally wears the kids out, and the parents can be entertained, too.
The cars that run on racesets are not compatible with most raceway slot cars, and the track conditions that work for the "set" cars are wrong for "raceway" cars. This produces a constant conflict. Generally the raceway has to have separate facilities for them or specialize in one over the other. Some areas do well with either over the other, and I believe this is due to factors beside the actual slot cars. Enthusiasts interested in "scale" always believe it's the only way for the hobby to survive and grow, and I'm rather sure those on the wing car side would feel equally strong about theirs. We've stuck around the hobby because the subset that interests us continues to be. I'm not sure it would help the hobby if we could come to some mutual respect for the various factions and work together for the improvement of the hobby, but it certainly wouldn't hurt. Raceways and racesets don't help each others sales - they're nearly mutually exclusive - unless the raceway embodies what amounts to a supersize raceset. Racesets sell more racesets (maybe), not interest in the typical big-wood-track raceway. The successes are more often exceptions rather than rule.
I've noted the comments regarding many of the 60's participants were kids playing, not seriously competing with one another. I agree. My observations as an adult in later years is that the adult competitive sport slot racing has become has actually overtaken slot cars for fun. Competitors have become so serious about placing well and winning, that's the entire focus. The hobby seems to have turned into the successful serious few and the disgruntled rest of us. Maybe this is why club racing seems to be increasingly popular; a greater emphasis on having a fun social activity than "dog eat dog, winner take all" race.
I'm a player, not a racer, a retired engineer that likes to build race cars and experiment. I'll never have what it takes to win a serious race, though I may know more about what it takes than some serious winners. It's a fun learning experience, a pass-time I enjoy that keeps me active. I currently have a stable of nearly 50 cars, most wing cars of various types, some not even for any sort of competitive racing class. I spend a lot of money at raceways I travel to all over the US as well as in special orders to my "local" raceway 125 miles away. There may be serious competitors that spend as much or more than I do, but I'm also aware of a sizeable class of racers they look for every deal or way to spend less money to go faster, often to the detriment of the raceways in which their hobby/sport depends. Our hobby also seems bent on making things as difficult and complicated as possible. Tracks that look like pretzels; cars that are poorly designed for racing around a pretzel. This maybe great for limiting competitive success to a select few. Do we want our hobby limited to a select few? I read comments regularly that expound on not limiting but expanding the participant base. It's frustrating for kid and adult alike to have great difficulty mastering. Remember the 15 minute entertainment? If one spends 13 of those 15 minutes chasing the car which deslots at every corner, do you think we'll be back for more? And it's not just speed. Actually if you look at how kids react when they see speeding slot cars, you realize that speed is a great attractor. There's a need for speed - at least in some moderation. Race set manufacturers build tracks with steel rails and cars with magnets to keep them on the track. Wings keep cars on the track. In the 60's, AMRC built tracks and guide systems with "slot-lock" (T-slots) to keep cars on the track.
Oh well, I've rambled on long enough. I usually keep off my soapbox, but the last entries in this thread touched a chord, and I've exposed myself to add 2 cents worth. My apologies if I've offended anyone. Let's all have fun and keep slot cars alive. I'd like to get a few more years in before I get too old to build cars and travel to distant raceways. My wife says she'd join me building a model railway in the space where my home wing car track now resides, but I have this need for speed that model railway doesn't satisfy. Maybe when I get too old.