His last posts didn't look like someone who was planning to leave. That makes me think he either got an accident, or is in prison.
Or, my personal favorite: Satoshi is a time traveller who went back in time to create Bitcoin, and is now spending his fortune in his own time.
The posts on this forum cannot be taken into account exclusively when it comes to trying to understand the reason why Satoshi left the forum, and for some time (allegedly more than 1 year) he was in contact with some developers after he wrote the last forum post. In addition, history tells us that some very close associates of Satoshi at one point took a very negative attitude towards him and demanded more
"decentralization".gavinandresen: I just wish I could convince [Satoshi] to switch to a more collaborative development model.
Tritonio: what do you mean? what is the current development model?
jgarzik: mostly-closed. open source, closed development
gavinandresen: Satoshi is the gatekeeper right now, all code flows through him.
SourceOf course, for all those who want to know the real history, which is very likely the closest to the truth, everything can be found in perhaps the best article written on the subject, which also has direct links to all relevant links. Satoshi logically decided to leave/disappear after everything, because when the majority attacks you and doesn't agree with your decisions, what else is left for you?
Software version 0.3.19, Satoshi’s last, would arrive the next day on December 13.
Read now like the final public message from Bitcoin’s creator, it seems tactical that he chose to wind down measures taken in the wake of the value overflow exploit, a sign he might have felt his mission to lock down compromises to the code had been realized.
Still, it’s difficult to say if Satoshi’s decision to walk away was his alone. After all, over the year, there had been a dramatic change in tone toward his leadership.
As to whether he intended to leave, however, Satoshi was definite, his sign-off observable when he removed his name from Bitcoin’s copyright statements[X]. Thereafter, he would also update Bitcoin.org, adding the names and emails of other developers – including Andresen, Sirius, Laszlo and Nils Schneider (tcatm) – to its contact page and removing his own[X].
What little we know about the transition was represented by Andresen publicly when he claimed a week later to have received Satoshi’s “blessing” to start “more active project management.”[X]
In the interim, Andresen assumed the trappings of authority, putting out a “help wanted” post and making clear to new volunteers they would now need to move the project forward.
The Last Days of Satoshi: What Happened When Bitcoin’s Creator Disappeared