"Our self-indulgence has many supports. It is indeed part of our nature; that is, in the body and soul, in our external life and our entire way of life in general. Such indulgence of the flesh comes in various forms. For example, there is sensuality, luxury, lustfulness, love of merrymaking, fondness for pleasure, trouble and care over everyday things, love of honor, love of power, perceptible success in one's affairs, and prosperity. There is a desire to be outwardly attractive, have valuable connections, and be sophisticated in external relations. There is a fondness for the arts, learning, and ventures. All this in the various forms constitutes a firm support for our selfishness, which, with certainty in its reliability and solidity, calmly rests upon it and, being amply nourished, grows from day to day, in one way chiefly in one person, in another way in someone else."
I am a professional artist. I feed my large family from my original paintings which I sell to galleries.
Would I be able to continue in my profession if I was to consider becoming Orthodox? When I visit my galleries to do business I have to be concerned about what I wear. It seems that St. Theofan is saying these activities lead to selfishness.
Ascetics sometimes go overboard and they should be read accordingly, sometimes you just need to dismiss some of the things they say as well-intentioned, but misplaced, fanaticism. Not only would I say he goes too far in his rash condemnation of the arts, but also in his condemnation prosperity and of love of merrymaking, the latter of which I would view as a virtue. Then there's his condemnation of learning; I guess ignorance is not only bliss, but also seems to be virtue...LOL. I wouldn't worry too much about your career and I'd recommend balancing your reading of Ascetics with some of the more Academic Fathers of the Church, such as St. Clement of Alexandria, St. Athanasios the Great, or the Cappadocians.