While art is the expression of human creativity, it doesn't require an artist to make it... nor does it necessarily make one an artist. While there are many valid motives to create art, there is one kind of motive that's considered more 'pure' than others -- the love of the creation of art. Anyone can learn how to draw one simple character, but there's a indefinable quality difference when the person really cares about the creation of the art.
There is a mental aspect I've always called "the artistic mind" and more recently just calling it "the creative minset" to describe a particular personality that seems endemic among creators of art. The creative mind isn't locked into ruts of accepted thought, it thinks 'outside the box' at things in new and different ways, it creates regardless of whether the person wants it to or not. The creative mind can't not create, the person has feelings of frustration whenever they run into a block (mental, physcial, economic, etc) that hinders getting that creation out. Art isn't always an easy thing to do, and the creative mind has periods of anxiety interlaced with brilliant flashes of clarity. Some pieces are easier to do than others, a piece may drive an artist to obsession in their need to bring it into the world as close to their vision as possible: other pieces require little effort and are almost an unthinking habit. But the need to create, the need to improve is always there. I've never met a creative-mind personality that was ever completely happy with their work -- they always see the flaws in their finished piece, they may be pleased with the general result but see ways to improve it for the next time, etc. Their art has a vivacity that isn't defined by technique or cost of materials -- it can be greatly disturbing or refreshing or thought-provoking or just plain fun.
There is another personality we'll call the "financial mind', a person who sees a market opportunity in everything. This isn't a bad</b> mindset, mind you, but it does have its drawbacks. Everyone sees The Scrooge as the far-end of the financial-mind's extremes, the person who becomes so wrapped up in their avarice that they cannot see the beauty of the world around them. Art for money's sake isn't a bad idea in and of itself; after all, it's always more rewarding to make a living doing something you enjoy. But there's the next level closer to Scroogism that has a person doing art only because</b> of money, a "get rich quick and easy" method to financial happiness. Ironically, most of my acquaintances who have this financial-mind in furry fandom tend to be the least happy around, notorious in their grumping about tight-wadded fans and stumping for a dollar anyway they can. They become the used-car-salesman of the art world, and most people (even the non-creative types) seem to be able to detect a lack in their art... something's missing. It doesn't remove any entertainment value, but does seem to change the significance value to many. Their art tends to sway with the fads, trying to follow (or create) a market. Subject matter may prove odd at times as the real world is a truely fickle place and what might be a safe-bet one season doesn't necessarily sell the next.
I guess that's why the phrase "selling out" implies an artist has mentally died, when the creative-mind has been supressed by the need for financial security to shift to a 'financial-mind' mode... and why so many creative-mind artists suffer a downward spiral when they do. As I said before, the creative-mind needs to create, and when it can't there are serious health repurcussions, mental, emotional and physical.
Like the financial-mind, there's another personality that has pitfalls, call it the 'fame-minded'. There are folks out there who honestly believe if you become famous, the world will stop being such a cold and impersonal place. Fame = sex, Fame = love, Fame = fortune, and so forth. Believe it or not, there are folks who become 'an artist" solely for the purposes of attracting willing sexual partners. Any 'creative-mind' artist finds the whole concept silly... face it, geeks were never considered the model of virility that every woman would fall over for. Conversely, the number of budding actresses who spread their legs to get into the right places is legend... and it still doesn't guarantee success or fame. It's good to have ambition, otherwise you don't have direction. But to focus your every being on essentially the approval of others for your worth is a doomed prospect from the beginning -- you are only setting yourself up for a fall if you don't get the attention you crave at the speed you crave it. And sadly, we have seen the repurcussions of the fame-mindset broken: they tend to view the world through a bitter lens, believe everyone else desires the same thing they do and scorns anyone who actually succeeds in it. If they can't have positive attention, they shift to negative attention. In art terms, in their bright moments they go for whatever they think is 'the prevailing wind", what would attract people and make them notice; in their dark aspect they go for the shock-value, tearing themselves and everyone else up in an attempt to be remembered for anything. Their art has meaning, but not necessarily one that would compell a long-term audience (except, perhaps, in the train-wreck kind of way).
Lastly among the dark side of art motives is the most insidious: Technique. Also called Art for Art's Sake, I call it the semantic-mind. Again, attention to detail isn't a bad thing, in and of itself. Becoming fluent in a specific technique is often the stepping stone to developing new techniques. But, as the phrase goes in techie circles "there comes a time to shoot the engineers and begin production". Too much attention to detail, too much detail and the point of the art gets lost. And semantic-minds tend to get fixated on such small points that it becomes difficult to lift their eyes to the horizon -- arguments about the 'validity' of such-and-such becomes religious battles. These become the Art Snobs, the ones who pidgeon-hole everything into neat boxes, a place for everthing and everyone in their place. Art done by the semantic-mind can be gloriously complex, hyper-realistic, subtley nuanced that would require further study to see all the points... it can also become so crowded that the meaning is lost, or so stiff that it feels caged. These often become the Artistes, the imfamous goth-artists who have something to say, if you can wade past all the layers to actually see it. They bemoan that nobody understands them, because they've narrowed their world down to such details that they've become unintelligible themselves.
Now, I'm not elitist to believe that creative-mind artists are the only artists worth patroning, be them illustrators or dancers or musicians or writers or whatever. But the psychology behind the making of the art shows through more often than not. In the extreme cases it is so blatant as to disrupt any enjoyment of the art itself, which would seem to destroy the point of making the art in the first place, at least from my point of view.