Billions is the currency that guys like Zuckerberg trade in. In this case Facebook allegedly paid off the FTC when it fact Zuckerberg should have paid it. So

Billions is the currency that guys like Zuckerberg trade in. In this case Facebook allegedly paid off the FTC when it fact Zuckerberg should have paid it. So Zuckerberg just pays back FB the four billion and everyone is happy. It's like you and me trading nickels.