Quite simply Satoshi realised if he was right, and he likely was, that he had to be anon. Can you imagine the target he painted on his back. Think it through
[1] Near 1 million BTC, he could easily become the worlds most wealthy individual by some large margin.
[2] Imagine the govs/corps after him + alphabet agencies. The guy just solved an a major problem, and the solution borders on genius, not saying its perfect, but it was original thought.
[3] He/She/It planned this out for a long time and thought it through. They are not in it for the the short term. They planned out no going public
[4] Avoid all the acolytes/nutcases.
Satsoshi would have no life left if he revealed himself. I think satoshi see's bitcoin at 1 Mill a coin [at least], and this is the reason for the 10e^-8, 1 satoshi = 1 cent.
"we" haven't done anything "wrong" that occurs in any system. We need a properly distributed exchange
It might not be the truth and only but the truth but my speculation is that he became disgusted with the community since Gavin showed it off to CIA, and become even more disgusted when he saw how twisted we are with our overly speculative, wanna-get-rich-quick-while-jerking-off mentalities and such.
My impression is that he doesn't give a single shit on any of us and more tragically even about Bitcoin. If not a prank, his recent post on not being Dorian, clearly shows he stepped forward to defend a man that was in REAL danger of being killed for his supposed wealth/ worshiped to death by the bitcoin fanatics.
Moreover, Sathoshi gave everybody the instrument, a decentralized currency but we somehow started to do it wrong (see MyBitcoin, Bitcoinica, MtGox etc)
But don't worry, Bitcoin will not burn in hell, only we will! (in a max of 90 years or so, and even less for some of us). And lets a keep a toast for for MtGox - Bitcoinica incidents as we love people being scammed of off their life savings.
PS: Haven't lost any bitcoin with the Mtgox fiasco but I have lost faith in the community. Protocol still works though.