It's reassuring to hear some others also talk about being socially knowledgeable and yet socially anxious and lacking close friends despite wanting them.

I don't think most people would understand that. I'm in my late 40s. I know how to interact with people on a casual level just fine. Although it can be exhausting (and not just in the typical introvert way).

I've been doing some personally challenging things lately and on one level they're almost easy to do procedurally because I know what I'm supposed to do and often do it well ... but it's so excruciatingly hard on me for what feels like small and glacially slow gains. I have terrible self-esteem and yet I'm bright and personable. Frankly, I suspect people might think I really have it together. But I don't. I'm so far below what people assume is the usual human experience. I'm a superficially high-functioning train wreck.

I dunno. I'm not really looking for advice. I know for me it's mostly a self-worth problem that's a personality disorder. I'm just babbling here. Maybe someone will relate.