Yeah, if you have any excess cash at all, put it into your arena.
Ideally you'd have an arena similar to mine but not so many bleachers. You realistically want to target something like:
Bleachers : 14500
Lower Tier : 5500
Courtside Seats : 500
Luxury Boxes : 50
You might even increase maximum if you increase the number of lower-tier to 8000, and dont even build any more bleachers. Depends on the money you have lying around.
And every game you're selling out is money lost!