The benefit that Han Xiao really wanted was to have the players spread the word of how attractive the arena was as a part of the main city, leading to more people coming to the sanctuary for it, bringing in a large number of immigrants and, more importantly, customers.
The Great Mechanic Han had quite a few more ideas, such as opening official bets and creating a PVP ranking system, both of which would attract more players. However, he thought about it and decided not to do that as neither of those was easy to operate and would only be official if they were made by the game developers. If an NPC like him did it, he felt that there might be some risks and negative impacts.
Most importantly, if he could give these rewards 'officially', he could make these studios and actors lose all their business. Han Xiao would never do that since one of his businesses in his previous life included that.