I am not surprised that sherdog is worth so much. They have a ton of members, lots of advertisements, writers/reporters, and they have a massive fighter database.
But they fail at having quality posters. I used to lurk there as a guest, but it got old. The good posters are very heavily outweighed by the crappy posters.
This website does extremely well for as MC previously stated, being only a forum. this place is awesome!