Your columnist was in Riyadh in 2016 when Muhammad bin Salman, wearing robes and sandals, announced his Vision 2030, aimed at ending what the crown prince described as the kingdom’s addiction to oil. Saudi Arabia’s de facto ruler talked of selling shares in Saudi Aramco, the world’s biggest oil company, to fund a giant sovereign-wealth fund (SWF), worth $2trn, to invest in diverse non-oil industries. He would be its chairman, benefactor…