Decades ago, when I was in high school, there were test prep companies offering classes (think Kaplan, Princeton Review, etc.). So the market for such is not just a recent thing.
My own SAT preparation considered just of reading the CB SAT booklet (that included the registration form) with a few practice questions of each type. Later, I saw a Princeton Review test prep book, indicating that Princeton Review was big on “gaming” the test. But most of the things mentioned were things that I was able to figure out on my own (and which any good student should have been able to figure out on his/her own – and can be taught in a short time to a student who does not figure them out on his/her own). So I am skeptical about the value of high volume test preparation classes that likely means a lot of work (doing thousands of old SAT questions or memorizing thousands of supposed SAT words) for a few points.