How do you expect to be successful at anything without being somewhat social?
Of course if you want to live a quiet life and avoid socializing very much, and want to be a successful independent contractor, those might be fairly incompatible goals.
We are talking about what is essentially sales and marketing skills.
I am the life of the party but I would never try to freelance because I hate sales and marketing so much.
This is all really asking how to start a business without having to do sales and marketing. Obviously, that is not going to work.
One can either gain these skills or do something else.
I'm certainly not the classic stereotype of the outgoing sales rep (whether that's a fair stereotype or not) but that didn't keep me from attending a ton of conferences, customer meetings, and giving public presentations.