Elon Musk has become the world’s first trillionaire following SpaceX’s record-breaking IPO, creating a fortune unlike anything seen in modern history. Nobel Laureate Paul Krugman and Yale economist Natasha Sarin argue the milestone is about far more than one entrepreneur’s wealth—it reflects how today’s economy rewards ownership of rapidly-appreciating assets, and exposes the limits of a tax system designed more than a century ago. Bloomberg wealth reporter Ben Steverman notes that while America has seen fo ...