Many people caught up to Harkensen III in the past few days. All of the hype surrounding the honor duel between Captain Orfan and Avid Serpent attracted lots of mech fanatics.
The underground arena made a killing by selling tickets at inflated prices. The demand for a seat was so huge that the arena decided to add floating stands to the arena in order to stuff as much people in their venue as possible. They intended to make the best use of the open space above the arena!
Part of the reason why tickets became hot was that underground arenas prohibited any broadcasts and recordings. Even though the authorities didn't care about shutting them down, the underground still needed to remain out of sight from the public. The underground arena utilized loads of jamming and interference technology to uphold this custom.