This is kind of a side note, but have you never learned an ability or tried to master a skill in secret? There's nothing wrong with being motivated by social capital, but if you extrapolate out from that to assume everyone is primarily motivated that way, you might be universalizing a personal trait that isn't really universal.

There are a lot of things I practice and do alone that never get exchanged for social capital: drawing, I play single-player games, I cook. These are activities where I either master a skill on my own (sometimes purely for the intrinsic motivation of mastering it even though it produces no value outside of that), or because (in the case of things like food/personal-programming/etc) because it produces "value" for myself that isn't exchanged with anyone else.

I'm not saying community and social capital doesn't exist, but if you are defining value purely in a transactional sense, you are missing out on a lot of human motivation. People do things alone without ever entering into a community around those activities or showing the results to anyone else.