Where did you get that the number of federally funded graduate students is 3.1 million?
Note that many will have industry, international or self funded (for MS it is less common to have funding). The 9B figure for maintaining the F35 you just said is very close to the entire annual budget of the NSF. Which is the main funding source of most of non medical research.
Also we are not talking about military budget, just the F35 maintenance program here.
The $9B figure is total amortized to yearly: research, development, production, and maintenance across the near century of lifetime (1990s-2080s).
I took the total number of graduate students, to spread the money across them. We could also look at the same number as, eg, funding an increase from 3.1M to 3.3M or 3.4M graduate students.
I stand by my original claim:
A 10% increase in graduate salary or number of students doesn’t justify dismantling our air force.