Could it be because the organizers kept the costs down?... which is the smart thing to do. I suspect that it was profitable not because the revenues were much higher, but because the Convention Center gave a heck of a deal, and in addition, the headliners did not charge an arm and a leg. Controlling costs is the best thing that can be done, in order to be financially successful in this convention business.
These are just my guesses, since I have not seen any books or records.