There are a gazillion things, a gazillion truly different and differentiated thing, a gazillion things of genuine value, to be the best in the world at.
This is exactly what I've been trying to say. Best in the world just refers to the world of the consumer in that moment, and best means the thing that most appropriately fits his worldview. In other words, I don't think you have to be the best in the world at classical violin. I think you can do great by making the best espresso on this particular block of downtown Chicago, or being the politician with the best stance on immigration (the one I agree with the most).
Compromise is the enemy of that. So is fear. So is the desire to fit in or be average. Overreaching is possible, but talent is almost never the problem.