You are now encountering the concept of a safe withdrawal rate. If you have money and want to spend it effectively, the best course of action is not to immediately spend it all, but to invest it. Then, once a year, you'll want to take the profits, reinvest a sufficient amount such that your capital doesn't depreciate due to inflation, and then to spend the rest. A more conservative strategy would have you reinvesting even more.
What's the point? Well, suppose you have $100. You could spend it all now. Or you could invest at a 7% profit rate, reinvest 2% for inflation, and then spend the remaining 5%. This lets you spend $5 a year, inflation-adjusted, for the foreseeable future -- so if your timeframe is longer than twenty years (20x5 = 100), it makes sense.
That's not to mention that having a lot of money in investments gives a school substantial practical/political power.