We can only theorized as to why Satoshi left, is it because he was afraid that the government are going to put him in jail? Or this is his plan after-all? left the project to the hands of few selected developers in the beginning and pursue other things?
Or maybe Satoshi has died already and that's why no one can access the supposedly millions of bitcoin.
he's probably dead... look at who the top possible Satoshis are, Dave, Hal, or group of them
i think time is proof that the single person of Satoshi is dead, or if Satoshi was a group, they'll never to be combined/agreed/Satoshi'd again