If you know a lot about twitter, it should come as no surprise to you that Evan Williams is the company's biggest shareholder. With about 15% stake in the company (more than his co-founder Jack Dorsey), he will probably become a billionaire when the company goes public. It's funny because the other guy actually was the one that came up with the idea for real-time mass txt messages, but he wasn't the one to own the company that created Twitter, Williams was. Currently, Twitter's private market cap is sitting at $10.5 billion. The company's going public will push Williams' net worth up to $1.5 billion, if it goes public at the same evaluation. If it opens higher than that, well, you do the math. It's awesome to see when someone made a good business move at the beginning of their career, stick with their guns, and emerge winning on the other side.