I, along with a lot of people, joined HN in 2008 after Techcrunch wrote about it. That's pretty close to "Group 2 joins" and yet 9 years later HN persists!
I get the feeling a lot of group #1 left in between 2010 and 2012. There are still tons of folks here who made accounts on day one, but a lot of the more conservative or libertarian leaning folks seem to have migrated to other communities around that time.
