But what's in it for the co-founder? Usually it's that they have lots of power over the company, e.g. being a CEO, and have more freedom than someone who still has to prove that they deserve that power. Jeff Bezos for example "only" owns 100 billion USD but controls a 800 billion USD company, with the freedom and power of a cofounder. After a certain amount of money, say 10 million, you can fulfill most of your dreams. And there are plenty of people who have that amount. But few can say they are in control of a 0.8 trillion dollar company.
As the other comments point out, Travis was kicked out though so he lost his power. So it's only understandable that he diversifies his portfolio.