there are billions in the bank and there will be more and more.
For a "heavy" plane, the parking fee is very small compared to how much money you can make.
yes, you can reduce the multiplier.
however, the money spent would not increase from it. Maybe an extra advanced finance level would be nice? more costs, expenses, fees, higher fuel/catering/staff cost?

https://massport.com/hanscom-field/oper ... ting-fees/