There is no value to the red canvas; there is only value in the conversation you're able to have about the red canvas, and especially value in controlling that conversation (and where/when it happens) by owning the red canvas.

I.e., modern art is valuable in part because people will go to art galleries and museums to stare at denotationally-valueless art if it gives them an excuse to talk/think about art history. Art galleries and museums are willing to buy those pieces to capture that foot-traffic, which gives a price to the pieces.