He should dump that stock or sell the entire thing. It is not a sustainable long term company like google. These social media sites are only popular for a generation or half of one. You can already see it. My Space was all the rage; now you are a dinosaur using my space, then faceboook was cool but then old people started using it so the faggot millennials moved onto twitter; 10 years from now; people won't give a damn about facebook and the ones that do don't click on ads or any of their fake advertising.
Why not just get out and be a billionaire in CASH and live your life. Guy is very young. That is what guys like Mark Cuban do. Get rich and the get the hell out. Websites and technology can be worth billions 1 day and lose half its value in a few months.