u/Ok-Sundae-1191

SpaceX is trading around 30 percent over its IPO price, giving the company a $2.3 trillion market cap. Elon Musk’s 82% stake would imply about $1.9 trillion of SpaceX equity alone. For scale, one trillionaire = a thousand billionaires. There are roughly 1,000 billionaires in the United States. Musk's wealth essentially equals all of their wealth combined.

John D Rockefeller, the previous record holder, was worth around $400-$500 billion (today's dollars) at the height of his wealth, representing about 2-3% of U.S. GDP. Musk's wealth is equivalent to about 5-6% of U.S. GDP. 

Edit: many have pointed out that I was wrong about Elon's stake in SpaceX. They are correct, and I admitted that down the line in the thread. He has approximately a 40% stake in a $2.3 trillion company, which gives him about $920 billion. When you add in his stakes in Tesla and other ventures, he is still well north of $1 trillion. Apologies for my math error. The 82% I referenced is his voting shares, which means he has near total control of the company. But the point remains: $1 trillion is equivalent to 1000 billionaires. There are fewer than 1000 billionaires in the United States. If you remove Musk from the pool of billionaires, the total wealth of all billionaires in the United States is about $6 trillion. Musk himself is perhaps worth about $1.5 trillion, or a quarter of the worth of all other US billionaires combined.