Last week when I mentioned that Second Life was popular with some twentysomethings (contrary to the common assumption that SL is a Gen X-only phenomenon), metaverse consultant and ex-Linden John Lester very reasonably asked for demographic data. I checked with Linden Lab, but for whatever reason, they declined to release current info. However, back in 2008 they did, and I happen to have those reports in archive:
In 2008 (as shown here) 25% of the userbase was 24 or under, and 35% were between 25-34. Assuming half of that age band were then 25-29, that's another 17% in their 20s, give or take. So in total, in 2008, roughly 43% of Second Life's user base was in their 20s or younger. (To estimate conservatively, let's round that down to 40%.) Assuming a 10% or even 20% dropoff in the last 3 years, the twentysomething population of SL now would still be significant. Given Linden Lab's recent advertising campaigns emphasizing vampire roleplaying games in Second Life, it's even possible the number of young Residents has actually increased from 40% since then, or at least remained relatively stable.