It seems to be implicit in your model that funding for political parties is a negative-sum arms race.
What army1987 said. The specific assumption is that on the margin, the effect of more funding to both sides is either very small or negative.
In my own view, the most damaging negative-sum arms race is academia.
This is definitely an extendable idea. It gets a lot more complicated when there are >2 sides, unfortunately. Even if they agreed it was negative-sum, someone donating $100 to Columbia University would generally not be equally happy to take $100 away from Harvard. I don’t know how to fix that.
What army1987 said. The specific assumption is that on the margin, the effect of more funding to both sides is either very small or negative.
This is definitely an extendable idea. It gets a lot more complicated when there are >2 sides, unfortunately. Even if they agreed it was negative-sum, someone donating $100 to Columbia University would generally not be equally happy to take $100 away from Harvard. I don’t know how to fix that.