Steve Ballmer, who was once Microsoft Co-founder Bill Gates' assistant and later became the company's CEO, is now richer than Gates. Ballmer is the world's 6th richest person with $157.2 billion in wealth, while Gates is the 7th richest person with $156.7 billion in wealth, Bloomberg reported. Ballmer, who retired from Microsoft in 2014, owns the NBA's Los Angeles Clippers.