He is definetely the brilliant clever guy

Nah, he's not "definitely the brilliant clever guy"...you're just succumbing to the natural human tendency to find connections and relationships between things that don't really exist.
His prediction was just a guess. There's zero way he could have created a financial model to calculate the prediction. He literally, just got lucky. And if he'd made some other prediction no one would have even remembered that he was wrong as we approach the start of 2018.
So you think his investments into twitter, Tesla, bitcoin and skype was merely a guess ?

Just one investment into Skype brought him $400 mln when it was sold to Ebay.
Also it was his idea in 1996 to automatically attach advertising messages to the bottom of outgoing Hotmail emails.