You are probably familiar with your fellow Texan Lance Armstrong. I just got done reading his biography and he says the exact same thing as you. Not so much from the perspective of that having cancer enabled him to win the Tour de France or something like that, but that given that choice, he would have had it just because of the way it got him to stand back and re-evaluate and look at the priorities in his life.
Well you don't learn anything from success. If you want to learn something about yourself, you undergo hard times or you fail because that teaches you something. And maybe you don't want to find out what you're going to discover. You hope that if you're placed in a moment that is very difficult like that, that what you're going to find is that you will be an honorable person, and you'll do the right thing and you'll have some measure of grace and courage, but you don't know the answer to that.
I can understand why someone like Lance Armstrong, who is obviously a superb athlete, the success just keeps rolling. But understanding how to balance that success and have a more real experience in life, not just as a persona, requires some work. And it's not easy. And you have to be able to step back and reevaluate and change your priorities. And that's hard to do, but it can be done.