The era of sky-high concert-ticket prices is exposing pop music's middle class — or, at least, who isn't among the 1%. A slew of high-profile artists have recently made headlines for downsizing, postponing, or outright canceling their arena tours, from heartthrob Zayn Malik and chart-topper Post Malone to legacy girl group the Pussycat Dolls, who were refreshingly candid with fans about why only one of their scheduled US dates would go ahead. "When we announced the PCD FOREVER Tour, we hoped to