If it helps it's worth noting that the "$1bn" is split between stock and cash
My guess is a "small" amount of cash - a few tens of millions of dollars, which I'd certainly not piss on and set fire to, to be sure - and almost all of it in stock. Which given that it's Facebook stock and other than Apple they've got to be edging the most ludicrously over-valued company in the world is most likely going to be worthless relatively soon.
Me, I'd flog the stock off right now while people still seem to think it's worth owning, unless there's something in the contract forbids that. But this may be why they've just earned $1bn in cash and stock, while I'm talking about it on a puerile digital arts forum.
You see where I go wrong is I write applications that have an element of complexity I charge people money for them. All this time all I had to do was write a set of photo filters and give the app away - then i'd be worth a billion dollarpounds of imaginary currency.