It's been speculated that satoshi disappeared around the time the CIA became interested in Bitcoin. Gavin Andresen wrote that he was invited to present Bitcoin to the CIA. Satoshi stopped being active around that time I think. One might say that he wasn't comfortable having the CIA look more closely into his work so he handed over control to other developers and left.
This.
Gavin will visit the CIAArchives of emails from Satoshi to Gavin Andresen.
https://www.bitcoin.com/satoshi-archive/emails/gavin-andresen/https://gavinandresen.ninja/eleven-years-ago-todayWe will never know the real reasons of his disappearance.
Subject: alert key
Satoshi Nakamoto
satoshin@gmx.com26 Apr 2011, 10:29
I wish you wouldn’t keep talking about me as a mysterious shadowy figure, the press just turns that into a pirate currency angle. Maybe instead make it about the open source project and give more credit to your dev contributors; it helps motivate them.
I’ve moved on to other things and will probably be unavailable. Here’s
the CAlert key and broadcast code in case you need it. You should probably give it to at least one or two other people. There are a few long time users who are always around all the time.