One morning in January, Byju Raveendran sat in the back seat of his shiny black Cadillac as it sped through Dubai. Just three years prior, the schoolteachers’ son had appeared on the Forbes list of richest Indians as founder and CEO of Byju’s, then one of the world’s most valuable education technology companies. He was dressed casually in a T-shirt and jeans, while his driver, Hashim, was more formally attired in a collared shirt. Raveendran, square-jawed and muscular at 45, told me he typically...