The more you have of it, the less you see. What is it?

“Light”

Light allows you to see more clearly, so the more light you have, the more you can see, which contradicts the riddle's premise.

“Distance”

While distance can affect visibility, more distance does not inherently lead to less visibility in the way the riddle describes; it can also imply seeing things that are far away.

“Fog”

Fog can reduce visibility, but it is not the concept that increases in quantity leads to decreased visibility as the riddle suggests; it is a specific condition rather than a general state.