I appreciate the point being made from the outside. I have no social media persona (a decade-old defunct Facebook account might be it, plus HN which doesn't feel social in the same sense), yet I don't feel that I'm homeless in the virtual space. I simply don't inhabit it, and I don't feel that I'm missing out.
I've wondered about this - but how do you know what you are missing out on? For example, if you were active on twitter or LinkedIn and carefully cultivated those profiles, who knows what life changing connections you may have made? (I've seen several people comment on getting jobs, business partners, fellow hobbyists, etc. on twitter.)
*edit: missed a word