If you read some of the earliest posts made by Satoshi in the original cryptography mailing list, you can find many conversations that happened between him and Hal Finney as well as a few other members of the cryptography community at the time. They're pretty insightful and definitely worth a read. And unless he's the type of person who talks with himself, I doubt they are the same person.
One of my favorite conversations is this one where the two discuss the possible future value of Bitcoin:
http://www.mail-archive.com/[email protected]/msg10142.htmlOne immediate problem with any new currency is how to value it. Even ignoring the practical problem that virtually no one will accept it at first, there is still a difficulty in coming up with a reasonable argument in favor of a particular non-zero value for the coins.
As an amusing thought experiment, imagine that Bitcoin is successful and becomes the dominant payment system in use throughout the world. Then the total value of the currency should be equal to the total value of all the wealth in the world. Current estimates of total worldwide household wealth that I have found range from $100 trillion to $300 trillion. With 20 million coins, that gives each coin a value of about $10 million.
So the possibility of generating coins today with a few cents of compute time may be quite a good bet, with a payoff of something like 100 million to 1! Even if the odds of Bitcoin succeeding to this degree are slim, are they really 100 million to one against? Something to think about...
Gotta love this part:
It could get started in a narrow niche like reward points, donation tokens, currency for a game or micropayments for adult sites. Initially it can be used in proof-of-work applications for services that could almost be free but not quite...
...It might make sense just to get some in case it catches on. If enough people think the same way, that becomes a self fulfilling prophecy. Once it gets bootstrapped, there are so many applications if you could effortlessly pay a few cents to a website as easily as dropping coins in a vending machine.
As for what Satoshi did after he left the forums, I've even heard rumors that went on the develop altcoins. I know it's quite popular for altcoins with mysterious devs to claim that they are actually Satoshi in disguise. The Bytecoin community toyed with the idea. NXT did so as well. Others believe that he is actually Nick Szabo who seems oddly enthusiastic about Ethereum...