People buy that kind of stuff because they're looking for the secret shortcut. Anybody that's been playing guitar for a reasonable amount of time knows there are no shortcuts. Efficient ways doing things and practicing yes but as you stress it takes years of repetition. Magic secrets to overnight success will always outsell hard work, but rarely produces any kind of success. Even when people do succeed using that kind of nonsense it's likely as a result of their own work ethic rather than the system. You're honest and that's a good thing. Your students respect you and acknowledge you whereas money making gurus make their money and are ridiculed later down the line. I'll take the respect of the money every time. Too bad it's so hard to get both.