because commoners believe art should be something holier than thou or the equivalent of. that its ideas and expressions should live up to the pedigree of work required to produce it.
but when you are presented a painting that's just red with a few shades (rothko), a painting that's just a few colours (Who's Afraid of Red, Yellow and Blue), a literal urinal (fountain), or a banana duct taped onto a wall (comedian)... it can be easy to scoff at the absurdity of it all, especially when the banana was sold for 6.2million usd. even the street dealer selling fruit was shocked at that price.
if you asked me, art was always about the ideas and expressions first and foremost. the physical media was just a means to convey it. not many people will see it that way, though. with the banana going for that much, it was always a rich man's game.
