Ok...
1. The economy is fine as it is.
2. If altering to the economic model needs to be done in the future the BBs have thought about it and have prepared methods to deal with any instability.
3. Everyone please stop arguing about this it is an issue that has been WELL covered in the forums and long posts explaining each individuals economic reasoning does nothing to convince the BBs. (I know I have been there)
You will all see that economic success is not that difficult. Play a season or two and you will find out how to develop and be a great success.
I can only say that you need to find a balance between 'training and selling' AND upgrading your arena. Do not neglect either or you will enter the red zone and be shot for bad management. ;)