Here is the problem with your complaints, they are for an extremely small portion of the entirety of the NBA's viewing audience.
First off, you are assuming most people buy tickets to games at their favorite team's home arena to see superstars. That's a bad assumption. Most season ticket buyers buy tickets to watch their favorite team play, not just because they want to see certain players, though that is a draw but a very minor draw. You can see this in just the Celtics attendence which has barely fluctuated since 2007-08, regardless of if the team had a star or not or was good or not. Most fans, especially season ticket holders, follow the team and watch the team.
I also believe that the very vast section of the viewing audience accepts that injuries happen and that when you buy a ticket, you run the peril of not seeing every player on either team perform.
Players get hurt. Players get sick. Players have family members die. Players get suspended. Players need time off to handle personal matters. And players need time off to rest because exhaustion is a real thing and needs to be managed. If you buy a ticket, these realities need to be accepted by the person buying the ticket. As the WWE like to say, and I think actually put on their advertising and tickets: "Card subject to change!" It's no different with any pro sport: Whoever is on the teams playing is subject to not performing for a large number of possible reasons, one being load management.
If you aren't happy with that, don't buy the ticket, someone else will, at least in most NBA markets they will.
If you are someone who watches your team on TV and a superstar isn't going to play that you like, switch the channel. Some people do this but judging by their robust ratings, people aren't switching off in droves because a player isn't playing. The NBA is losing some viewership, but not to load management complaints.
This load management stuff you are bringing up just is not a big deal. Again, ask the season ticket holders in Toronto if they minded Kawhi missing some home games this year to load management. Ask, Toronto fans who watch on TV if they minded Kawhi being load managed. Now go ask those same people in Golden State if they wish Durant was load managed. See what you get for results. This just is not as big an issue as you are making it.