The Earth has not been worn flat from erosion. It's a common misconception that erosion could flatten the Earth. Here's why:

* The Earth is a sphere: The Earth is a sphere, not a flat plane. Even if erosion was incredibly powerful, it wouldn't be able to flatten a sphere.

* Erosion is a slow process: Erosion, while constantly shaping the Earth's surface, happens at a very slow pace. It takes millions of years for significant changes to occur.

* Erosion is balanced by geological processes: While erosion wears down land, geological processes like tectonic plate movement, volcanic activity, and mountain building constantly create new land. This creates a balance that prevents the Earth from being flattened.

The idea of a flat Earth is a myth. There is overwhelming scientific evidence that the Earth is a sphere, and erosion plays a role in shaping its surface, but not in making it flat.