Would those charities be better off if Musk never existed?
He didn’t steal anything. He created something.   He’s just a visionary with the ability to act on his visions. 
I don’t think his wealth is “fair”.  But i know that his wealth is “good” for all of us collectively.  We’re better off because his wealth exists.  
https://www.foxbusiness.com/economy/...-tesla-charity