Elon Musk has created — and lost — more paper wealth than anyone in history, with most of that loss occurring in just four weeks. Nor is he poorer now than he was when his SpaceX shares were “worth” more than a trillion dollars. What has changed is how the public values what he owned: 5 billion shares of SpaceX (roughly 42 percent of the company). With only 4 percent to 5 percent of SpaceX shares publicly trading, market cap calculations fluctuate wildly. A 5 percent wealth tax levied at peak valuation would have hit Musk with a $55 billion tax bill.