I struggled with that too. Here's my mental model, which may or may not be relevant.

Imagine you're holding a penny directly in front of your eyes, between you and the sun. It can do a pretty good job of blocking the sun for you, because it's so close, but no one else is impacted.

Now move that penny a few hundred feet up. Now it's almost imperceptible, but far more people (technology permitting) are capable of spotting it.