Why do so many find it so hard to accept that you cannot see light?

You may feel certain that without light you cannot see things, but that does not mean you can actually see light.

This is important, pay attention... for most practical purposes it is quite acceptable to speak as if you "see" light, and when looking at streetlights, burning candles, bonfires and the sun, it appears as if you do.
But objects that emit photons of energy directly into your eyes are being perceived in exactly the same way as those you "see" with reflective light. Seeing is a creative process, an act that creates your screen of perception and presents a physically objective world around you. Note that well:-

Seeing is a creative process, an act that creates your screen of perception and presents a physically objective world around you.

By our habits of speech we tend to think of "seeing" as what we describe as visual appearance, but the screen of perception encompasses everything our senses create to formulate a world of existence.