No matter how much skill you have, or how much experience, good classes will bring you nose to nose with your inadequacies, and unless you are made of depleted uranium, it hurts. (See my
report of the Cave 2 class I just finished and didn't pass.) And in every class, there is a spectrum of capability. Sometimes it's obvious who the strongest diver is, and sometimes the strengths and weaknesses are so asymmetrically distributed that it's hard to tell. But everybody is there to try to learn to be better at something, and if the class shows you where you need to improve, then you just have to pick yourself up, dust yourself off, and get about improving!
My Fundies class had six divers in it, and I got put with the "these guys are hopeless but I have to teach them anyway" group. We were the three stooges underwater, constantly getting separated, having buoyancy problems, and misunderstanding signals. None of us passed. But I passed six months later, and one of my buddies later took the class over and passed it. And the skills we learned and the work we did was totally worth it.
As somebody just told me about the Cave 2 class, wallow in it a bit, then pick yourself up and rub dirt in it and get going!