Other than science, those are some very bloated and inefficient causes. $1 billion to Cornell? Aren't most of the prestigious universities already swimming in billions of dollars of endowments? He can do what he wants of course, but it would have been nicer if the money was targeted to long shot bets--that only a super rich person could fund--rather than normal things are already well funded through taxes.
Where else does research get done? Who pays for the buildings, where each one costs hundreds of millions of dollars? Scholarships? Who pays for new tenured positions?
Yes, administrative costs could be cut (I think substantially). But there's this long-going misunderstanding about the roles of endowments at American universities. These endowments have been budged into the next century of operation -- each year they are expected to generate some income to cover operating expenses. These expenses include salaries, financial aid, etc. The larger the endowment, the more income. They can't just drain the whole thing to pay for a building, because then they auction off the future for the present.