Very interesting dissertation.
It took me back to my grad scholl years. I remember this one Creative Writing class I took (don't ask me why, I was doing something else, but it was quite an experience) where every student there, even though they had not puplished anything yet, thought of themselves as writers.

Of course, the definition has been quite opened now, but in my view, to think of oneself as a (successful) writer is attached to a certain level of acceptance or recognition determined by publications, critics, sales, etc.

I think that no matter how personally we want to define success (be content with what you do regardless of people's opinion), there is an intrinsic social/economic element to the concept that makes artists dependant of public opinion and acceptance.