I would think about the biggest opportunities to help make the universe a better place, and look to see what efforts to do so were under-funded. Unfortunately,

I would think about the biggest opportunities to help make the universe a better place, and look to see what efforts to do so were under-funded. Unfortunately, while $5 million is a TON of money, it is tiny compared to, say, what the Gates foundation can throw around. So, it's either for small projects, or long shots. And the long shots are the ones that have a chance of being awesome. I'd try to put together a team to tackle the incongruity of the following two facts: (1) 1/3 of healthcare dollars are spent in the last few months of life, and (2) physicians and other health care workers do not choose this level of care for themselves. Would a multi-disciplinary team be able to educate people about how bad things work out when you try too hard late in life? This is about a trillion dollar problem, even a 1% decrease would be a huge net benefit to the US population. If I more time, I would probably explore other inexpensive, but potentially very high payoff ideas, like funding a grad student to look into practical ways of making blockchains work for auditable transactions (like smartphone based voting documentation and other government transparency). Another option, a free time-lock cryptography server. (E.G. release public keys whenever, private keys at predetermined times. Lots of utility in this space, but also government interest - If you are really serious, I have some more ideas, just not so much time right this second...)