As someone who has been a private tutor, the only advantage most kids got was that they passed the class badly instead of failing it. They were not standouts. The kids who are standouts - and I was one of them, which is why I was so recommended - need guidance sometimes, but largely get it on their own (and especially when they have to teach their fellow students - if you can't explain it, you don't really know it). I tutored a few smart students who were just weak in one area and needed to reinforce their basic understanding, but most of them just didn't care about wasting time and money, because it was my time and parents' money. I needed the cash, though. I never lied to parents about potential and I really tried to help. But there's only so much you can do when an ADHD kid won't attend to the lessons, or has some issues with their parents.

One of the things that modern life has messed up is the idea that you should always be happy. No, sometimes you just have to accept that what you are doing sucks, that you will have to power through it, and that's life.