When did the community ever have the power of the purse?
Never. By "community" we usually mean the editors. As far as I know, most donations come from readers, not editors.
I agree that planned investment can do better than 4%, and still be relatively safe, but needing the funds in the very near future severely limits investment options.
The usual method with endowments is to spend the interest, not the principle. Only the principle is difficult to access in long term investments.