If you want to sell art on the internet you need to be good at marketing.
Take someone like Steve, if he would paint something and wanted to sell it on this site he would get money, even while he doesn't has incredible art skills.
He has an audience.
Take someone like
xkcd - A webcomic of romance, sarcasm, math, and language - By Randall Munroe .
He sells art and make a bit of money with it. Dilbert comes also to mind.