If I was Satoshi Nakamoto, first, I will continue to stay anonymous, secondly, I won't dare send 1 million bitcoins to charity, and sell those for USD, for doing either of this two, or both, will vehemently crash the price of bitcoin, and send panic across the cryptocurrency market, which could lead to a greater dump, I will allow the bitcoins to continue to sit there in the wallet, as long as I continue to have much more than enough money than I will ever need to spend in my entire life, and even my children and my children's children.
And I might even pass on without revealing the secret phrase or private keys of the wallet holding those 1 million bitcoins to my children because their vision might not be the same as mine, and they might withdraw and sell the entire 1 million bitcoin, crashing and destroying the price of bitcoin and cryptocurrencies at large when I am no longer there.