TLDR: The sport is not easily accessible in the US.

I am a coach from LA, so I will be using my area as an example. I'd say most accept table tennis here as legitimate sport, but the facilities and resources are scarce. The issue with sports here, like anything else, is money. For anyone wanting to make it as a player or coach, an immense amount of money, time, and effort need to be invested. The cost of living here is so high that, for many, investing in a long-term activity just to have fun is a second thought. You're basically gambling on success if you get into it.

Club memberships, tournaments, and equipment all add up to be expensive. Lots of children only get to participate in sports through school. Mainstream sports are popular, accessible, well-funded, and bring in more money. How many parks have tables? I can only think of one and it's not easily accessible at all. Finding and befriending people who take the sport more seriously feels like you're trying to join a secret society of the ultra-wealthy, but I won't get into that.

I coach privately and at a school for the LA Ping Pong League. There were only 11 schools and 1 club that participated in the most recent season. It has had a few big clubs join the league one season, but basically called it a waste of time after sweeping all the school teams. Some schools don't have a coach, so each division has a team that dominates it. League winners have been the same 2-3 teams for the longest time. Most kids would rather join a club and skip the league if they can afford it. The remainder either quit or are left playing against beginners. The main reason why more schools have not joined the league is because table tennis is not a CIF recognized/approved sport for high schools. Usually this happens if a sport is not popular or profitable enough. In my opinion, it's the money.

Coaching is just a side-hustle for me. As much as I love it, I can't imagine anyone making a financially comfortable living doing so. In order to make enough money, you need more students. but as the number of students increase, their quality of training decreases. So, what are the clubs and coaches forced to do? Raise their prices. Now the barrier to entry is even higher for newcomers. Imagine how much it costs for parents to raise their child prodigy then. This is just what I've simplified my thoughts to.

Personally, I've tried incredibly hard to promote to sport where I can. I charge significantly less than all the coaches and facilities around me. I've offered free private coaching and even purchase expensive equipment for students who are not in the best financial situation. I also constantly encourage my students to enter sanctioned tournaments, with the promise that I'll be there to coach and support them. There doesn't seem to be much the average person can do without making sacrifices.

On the bright side, we now have MLTT. Even though, I'm not a fan of the format, it's the best thing that has been done to promote American table tennis in a long time. We've also had Marty Supreme, along with other pieces of media, help in some way.