“The first reality is this: However much it takes to become a top-flight classical musician, the performer can expect to earn only what the market is able and willing to pay. … Today, far more ‘people with money’ are inspired to give to charities meeting human needs than are willing to pay top-flight classical music performers year after year. … [U]nless and until society at large assigns higher value to the extraordinary work of classical music performers, musicians cannot expect to be paid what they deserve.”