Man of Honour
This sounds like me to be honest, I'm more than happy all by myself (so long as I have internet )
I own a small computer repairshop and can "turn on the charisma" as you put it when needed, that said I do have my off days where I can't really be bothered.
that said naturally I am a "chatty" person so will also quite happily stand and chew the fat with anyone.
My missus on the other hand would go mental if she had a day without leaving the house, she can strike up conversation with almost any random stranger quite happily.
So can I, but that's superficial and I won't do it in case they're offended and cause me hassle. I am social for my job, because it's part of the job. When I have a choice, I don't socialise at all. My idea of a holiday is to spend a week not talking to anyone or even seeing anyone. I usually end up leaving the house once to get some shopping done and if possible I'll do it late at night in order to meet as few people as possible and not have to interact with any of them. A holiday is a rest from work, so for me it's a rest from socialising since that is work.
I don't hate people. I don't even dislike them, on the whole. I'm pretty sure that an extremely large majority of people are at least reasonably decent people. That's certainly been my experience. Nor am I lonely. In fact, I think I am immune to loneliness because loneliness is essentially being alone when you don't want to be.
I wonder how many people are suffering from loneliness because they're been conditioned to believe they should be more social than they naturally are rather than because they don't have as much socialisation as would actually suit them. One size doesn't fit all. It rarely does.