This is an interesting subject and while I know I don't have "the answer", I do have some thoughts on the matter.  I think that art(small "a") is any attempt to produce, or reproduce, something in any medium which tries to evoke in the viewer a response of some kind, hopefully positive.  A student in school (1st grade or whatever) with the assignment to "draw a picture of your family" will invariably produce a crude drawing of their parents and siblings.  This is art, crude, unskilled, rudimentary, but still an expression in the given medium by an individual to express an idea.  This holds for other areas also, such as poetry, music, writing, and such, that can be accessed by any level of individual.  Art (Capital "A") is another matter entirely.  Here skill is involved with making the finished product, and the better the skill, the better the Art.  To consider that art is only what can be sold only shows the level of the buyer's understanding, not the quality of the work itself.  Art comes in many shades, colors, and levels, just as does literature.  That one can not appreciate a well written novel, or play, does not detract from the work itself, but shows only the level of the individual's understanding of what it appreciates.  And it is possible to learn to appreciate, and discern, the different levels, colors, and shades of any artform.  But, to produce quality requires skill, the more skill the better the outcome....true of anything, but especially Art.  Sales hype might produce revenue, but it doesn't produce Art.  So, in conclusion, I think that art runs the gamut to Art, and where one is on the curve, either as artist or owner, is a result of comprehension (owner) or skill (artist).  Like water, you find your own level.

Sunfish

i really like such concise and "pragmatic" definitions of abstract things! (a favourite is "reality is that which does not go away, when you stop believing in it")

thanks for the interesting link, and welcome to the forums