I see it backwardsly - the 5 people you spend time with are the ones most like my average. I'm not who I am because of my friends; they're my friends because of who I am. If I were willing to replace one of these 5 with another, I would still be me, but I would have a less-close friendship with that person.
This article seems to suggest we should all dump our current "go nowhere" friends and try to become PG's best friend (or friends with similarly accomplished humans). I counter with the Nash Equilibrium, that PG would exclude most of us, and we'd be stuck back at square one, having to be friends with plain-old each other.
The author himself whittled down his life to 2 other people. What a selfish and lonely life!