Four of the world's richest men stood together in the Rotunda of the US Capitol today for President Donald Trump's second inauguration: Meta and Facebook founder Mark Zuckerberg (net worth $211 billion); Amazon founder Jeff Bezos (net worth $239 billion); Google CEO Sundar Pichai (net worth $1.3 billion); and the world's richest man, Tesla and SpaceX CEO Elon Musk (net worth $433 billion). Bezos' fiance Lauren Sanchez is by his side.