If we knew who Satoshi was, we could find out if he has million-dollar yachts. And so, it is impossible to know what and who has it or not. In addition to the well-known BTC-address of the founder, there may be others.

Problems with spending (exchanging for fiat) cryptocurrencies in the future may become quite serious phenomena (without paying taxes like Roger Ver).

Or hopes for mass adoption of bitcoin as a means of payment may simply not come true and all the wealth will get stuck in the blockchain.