I just want to balance out your generally awesome response by noting that they may not be wired in a way that your comment is good advice (despite it probably being so for 90%+ of people) and that that's OK if they want it to be.
Now in my 30s, I don't regret a single second spent geeking out or learning things on my own earlier in life, but I do regret the mental anguish of thinking I "should" do X or "must" do Y because "that's what normal/healthy/sane/whatever people do." It just turns out I'm introverted and love a lot of time alone working. Now I'm thriving having embraced that. (I'm happily married, have a kid and large family too, so I'm not a Hikikomori or anything ;-))