I've estimated a lower bound of current Satoshi's fortune. My estimation is that he owns more than 1M BTC, or 100M USD at current change.
It is impressive, isn't it?
That's a good reason to stay anonymous!
He needs to remain anonymous anyway. This is all the power of Bitcoin. No manipulation to affect the coin. I think Satoshi knows the real value of his creation in the future. This is just the beginning. The price will continue to grow further and then it will have more than all the rich people in the world combined.
Probably he has some plan to capture the world. After all, the one who controls the money can do a lot.