He certainly had a way of bringing out the beauty in truth.
What he's saying here really is useful, since he's also recognizing the variation. He knows that he is not the median or mean, but a point somewhere in the field among other points. The median does not exist; it's only an abstract measure of the wide range of variation and commonality.
However, it would be foolish (or, as he puts it, optimistic) to place yourself blindly at the top of the bell curve without evidence to support that.
As Gould (bless his heart) says in the paragraph following that: "I possessed every one of the characteristics conferring a probability of longer life: I was young; my disease had been recognized in a relatively early stage; I would receive the nation's best medical treatment; I had the world to live for; I knew how to read the data properly and not despair."
He was a scientist. He had evidence and reasons for believing he lied where he did among the statistics. He didn't choose to believe that, he deduced it.
If someone has good reasons for believing they're going to be better than the average, more power to them. They're simply making an intelligent conclusion. But you can't choose to be successful by sheer willpower alone. You have to make a case for it; build evidence that proves it. I don't see that here. I don't see it with most people who believe this sort of anti-statistical nonsense. All I see is a misunderstanding of statistics; a lack of respect for the variation and where you are likely to lie within it.
You have to understand that before you try to do better.