I don't know is he had an insider info, maybe he's just knowing that the bubble will popped very soon. That's why he sold his coins, we never know what is the reason though lol. The thing is, what a good move from him, sold his coins at the top price.
Everyone is speculating by the words that he sold when the price of bitcoin was at an all time high valuation, we all know that the price of bitcoin was below $700 a couple of years back and anyone who sold bitcoin beyond a couple of thousand dollars would say that they sold when the price was at an all time high valuation, there is nothing concrete to prove that he sold when the market started to fall after the rally, i have not seen any interview in which he claims that he sold the coins when the price reached the pinnacle. 