Here is one of Chen's posts explaining that he left to go to school.
http://www.vbulletin.com/forum/showp...1&postcount=19
I also remember him saying he was leaving the world of 'virtual insanity' behind which is what online communities are sometimes.
He was also the founder of Hivemail.com which was an early email program with much promise and many users which he transferred ownership to another person (tubedogg) when he resigned. Though I do not believe Chen wrote the Hivemail script it was a decent script and ahead of itself at the time. Unfortunately the newer owner ran it into the ground for reasons unknown burning many users.
Chen was a good coder and a good leader of the community back in the earlier days.