Tesla CEO Elon Musk, the world's richest man, stands out from the other Americans who preceded him in holding the same title.Matt Rourke/APElon Musk is the world's first $400 billion person.It's not just his wealth that increased in 2024.Thanks to Donald Trump, Musk will enter 2025 with unprecedented power.Elon Musk is more than just the world's richest person.He's also the self-proclaimed "First Buddy" of President-elect Donald Trump, who will soon return to his position as leader of the free world.