Not every event is a success financially, even when the room looks full, there can be large costs behind the scenes. A bigger-than-expected artist fee.
Lower ticket sales.
Production problems.
Unexpected venue costs.
A cancellation.
Bad weather.
One problem can change the entire calculation, that's one reason organizing events involves risk. The audience sees a packed room.
The organizer might be looking at a completely different picture.
Sometimes a great night can still be a financial loss.