How is that impressive? Right now he has the potential to earn, and invest, 10's of millions of dollars that he can give away. Probably even make a self-sustaining endowment that can benefit people for many many years.
Why can't that be done by whatever organization he gives it all away to?
The Ford Foundation was founded in 1936 and is now worth $16 billion.
The Rockefeller Foundation was started in 1913. By the end of 2016, assets were tallied at $4.1 billion with annual grants of $173 million.