Big sites are usually run as companies where you have several people who own control of it. Its better in the long since, say its you and 4 other people who might be your friends (probability is likely thereof). 2 people might doing programming, 1 person might do photoshop, 1 person might be a linux admin and take care of the load balancing.
This how Facebook was started, it was just a 3 guys from harvard sitting around a kitchen table programming Facebook,
The guy in the middle is Marc Zukerburg.