One sentiment I hear quite often on this website is "real artists don't do art for money."
Putting aside the adorable naivete of this comment, the underlying assumption is that artists who sell their work are selling a part of themselves, in a way devaluing the very thing they create. To some, creation is the kind of thing only the gods do, and a monetary transaction sullies that divinity.
I can understand the allure of this opinion. It's nice to think of yourself as above such a petty thing as money. But I am more than a creator. I'm a consumer, and what I consume is food, and food is how I live long enough to create art in the first place. And even if I could make my money in other ways (for example, smuggling yaks), I wouldn't want to live in a world where every single bag, bottle and box of sustenance was devoid of artwork, nothing more than a flat, boring piece of typography (and it would have to be comic sans; every other font is a work of art in and of itself!). I don't think I'd like being treated to advertisements that amounted to "Buy this product" because no artists were consulted, no writers commissioned, to make that ad pleasing to the eye and worthy of my brain's attention.
These same folks more often than not believe artists are special, chosen, that if everyone could create art that art would start to lose its meaning.
There's something kind of distasteful and selfish about this attitude to me. I think of art as a language that makes the world more beautiful, or at least a little more interesting. Wherever you find it (and you can find it in places you least suspect) it's telling a story and doing its job. If you see commercial art as soulless and plastic and fake, fine by me, but I wouldn't care for the alternative - a world where art was planted like a flag at the top of a mountain and only the upper echelons of society could reach it and see it and understand it. Art on advertisements and soda cans and children's books may not seem culturally relevant or even always pleasing to the eye, but it has a purpose. It brings art to the non-artist. It makes life a little nicer.
(Besides...I wouldn't want to work in any other field. Getting to do what I love for a living is awesome, even if I am considered a sellout for it.)