I delineate my introvert / extrovert brain by classifying people I deem "interesting enough to talk to" and "people I'd rather not talk to". For this reason, work interactions always seem to go better than off hand social interactions. If someone is condescending or rude then I'd just rather not waste time talking to them. At this point in my life I don't really feel it's worth the effort to force social interaction in either direction, some people like you others won't - dating also gets easier if you take this approach.
Something I'm curious of is if "lonely" brains are less healthy? Also, for reference - the best point of comparison for social anxiety in my case is analogous to why I don't see the point in fancy cars. I drive a 2001 nissan, but I never worry about where I park it, if it gets dented or worry about someone keying it. If I drove a lambo, I'd constantly be worried (even subconsciously) about this kind of thing.