I don't necessarily think that's even close to impossible. You can always increase the specificity of a skill to the point where it's possible to become the best at it. If you want an example, it's near impossible for most people to become the best programmer (there can only be one), but go to github and pick a random library and pick the most active contributor to that library and you've most likely found someone who is the best at that domain. Then look at the number of libraries on GitHub. Then you'll start to see how many people are the best at a very specific domain of knowledge.
Sure, it isn't logically impossible. In fact, everyone is certainly the best in the world at SOMETHING, if you get specific enough (like, I am best in the world at physically occupying the space I exist in).... but that doesn't really mean much. Being the best at something only means something if what you are the best at matters.
I guess you could word that as "it means something if what you are the best at matters to you". If there is something that really matters to you, by all means do all you can to be the best in it. You will love every bit of it while you're trying (okay, not every bit, but you get my point), which will make you happy---for instance, I've never met a great musician who didn't look forward to and didn't love their practice sessions. And, as an added bonus, you might actually become the best, or really, really damn good. That must feel heavenly.
I don't necessarily think that's even close to impossible. You can always increase the specificity of a skill to the point where it's possible to become the best at it. If you want an example, it's near impossible for most people to become the best programmer (there can only be one), but go to github and pick a random library and pick the most active contributor to that library and you've most likely found someone who is the best at that domain. Then look at the number of libraries on GitHub. Then you'll start to see how many people are the best at a very specific domain of knowledge.