Just 4 Designers

How do these popular websites earn money like youtube, facebook or any other popular sites which dont earn money from advertisements on their portal. Then where do they get money from to survive or even earn handsome? Real answers Please!

Hello, I am setting up a new business which will benefit foreign students living and studying in London. I am hopefully wanting to gleen any information as to what paper publications or websites are most popular for this market.
Thank-you.