LeBron and Messi can't be replaced because they are playing by certain rules (working under certain conditions)

Elaborate? I see zero connection here.

We don't get paid only because we are highly skilled but because we achieve some outcome.

It takes skills to achieve the outcome. You can't just approach random teenager, tell him "I want you to build Twitter. I don't care how you achieve this outcome, just to it!" and boom, unskilled unexperienced laborer made you as good a product as anyone. Unless by "willing to do anything" you include willing to kidnap people to do the work at gunpoint or organizing a heist to steal codebase from competition, but that, in addition to being a comical stretch, would also require unusual skillsets to achieve successfully.