As you most players here are thinking BBW,the most players here are funplayers and not profiplayers,who want earn money with their games.If you want to see a professional site -with professional players too- look at www.playchess.com (client available),where sometimes 2000 players are online ( 100000 registered users- only chess) and Kramnik ,Judith Polgar and others are live playing.
Once again:For a big event you need famous names from the chessworld, and these players play for free and than many standard players are signing in (with fee) because they want play against the masters.