Why does atmospheric pressure decrease with increasing height in the atmosphere?

Imagine a section near the Earth's surface. For any given area parallel to the surface of the Earth, there's a large column of atmosphere sitting on top of it. The Earth pulls down on this atmosphere through its gravity (as it does to all objects). As a result, there is a lot of pressure on that area. Now imagine going up a 10 km. Now there is a lot less atmosphere above you at that point. The end result? Less atmosphere above you means less force pushing down, means lower pressure.