Disagree strongly with #6. It's too easy to find counterexamples of brilliant artists who've created immeasurable value and died penniless. Market value != intrinsic value.
The girls selected by the pretty sorority will likely be dumber than average but that's not because they are pretty, it's because of the selection criteria.
An attribute used in a selection requirement is easily misidentified as a causal factor. Pretty does not have to cause dumb. Popularity in and of itself does not have to cause bad music. Neither does starvation cause great art.
I must temper this conclusion with a joke: "I used to like the Chilean Miners when they were underground. Now they're too mainstream."
I wonder, though, if perhaps you are nit-picking on a pithy title? "Be valuable" doesn't have to mean "learn business at the expense of creating value in your music", does it?
Maybe it's like this: getting paid implies your work has value, but your work may value even if you are not getting paid?