Why dont these ultra rich people donate all this money NOW, instead of some indeterminate future. If you have 800 million why cant you donate 10 million a year?
Its not like any human being need a billion dollars to live
Typically they do. Tim Cook gave away $100 MM a year or two ago. Bill Gates has already given out a major chunk of his fortune to start his foundation. etc.
What this pledge is about is giving your fortune to charity on your death, rather than turning it into dynastic wealth.