Well, he is a rich man getting to this question a kind of a person on to me like it's my account it's my decision if I want to share the transaction I made on the site or to the app I used to buy bitcoin.
Not a bad idea to ask for proof but still, is the news to know not proof? that he really bought a billion worth of bitcoin there is much news who spread the word on Elon Mush bough a billion worth of bitcoin.
I would also think about it that maybe someone called from that site he used to make the transaction Elon Mush if he wants to share
Has anybody actually seen the Tesla purchase on the blockchain to prove it actually happened?..would be interesting to see it if it was a single transaction?