Jack Dorsey has become one of the most influential techology entrepreneurs in the world, joining the ranks of Steve Jobs and Elon Musk. He boasts the unique distinction of running not just one but two major companies, Square and Twitter. The dual role has earned Dorsey a net worth more than $4 billion, according to Forbes.

The 41-year-old is best-known for co-founding Twitter in 2006, but his tenure there hasn't exactly been smooth. In 2008, Dorsey was fired from the social media network he helped invent, before returning as its chief seven years later.

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