It took thirty years for Nvidia, an American firm whose chips power much of the world’s artificial intelligence, to reach a valuation of $1trn. Getting to $2trn took only nine more months. It passed the $5trn mark less than two years after that. It is now the world’s most valuable company, worth around $5.4trn. Next year its sales are expected almost to double. Some analysts predict it will take in $1trn in annual revenue by 2029. It is not just chipmaking that has spurred Nvidia’s stunning grow...