Let me start off with a theory- the things we really accomplish, that we want to be remembered for, are not ever for money or status. These are both transitory and a means to an end. I honesty feel that the desired end result is always borne out of love. I also feel- to not be too crass about it- blessed to be an artist. I can create,and display, images several times a day to the people who are lucky enough to know where to look ;).
Still, is it justified when an graffiti artist, such as Olek of NYC, puts up a piece in the streets,and then complains when it is "stolen"?