Art may make the world more beautiful, but one should choose a career in some profession other than art.
Conclusion (should)
One should choose a career in some profession other than art.
Evidence
How much artists get paid (if at all) is determined by subjective evaluations of their work.
It is unacceptable for one's pay to be determined by subjective evaluations of one's work.
Evaluate
We can synthesize these two premises together to derive the inference that, "It is unacceptable how artists get paid". That means that the author is assuming some Linking idea like,
What about coming up with a potential Objection?
Given that ... your pay is determined by subjective evaluations of your work, How could we argue that ... you should choose a career in art?
We could say,
It also seems like getting paid based on subjective evaluations of your work is something common to tons of jobs. Don't we often have performance reviews with our employer, where they decide if / how much of a raise we'll get?
Goal
Look for an answer addressing the missing link between "unacceptable determinant of pay = bad career choice" or one presenting some objection that allows us to argue it's still fine to choose a career in art (such as being okay living modestly in exchange for getting to do something you love).