I could start with MySql, Apache Wicket with Twitter Bootstrap and crank out that site in two weeks, bug free.
Actually, I also doubt that anyone could crank out this size of a site -- with this sort of user load, and with the number of systems you would need to integrate to -- even with a solid team of A+++++ players -- in anything less than 4 years.
Even Facebook evolved over a half-dozen years. Amazon, a dozen.