You can find streamers who will talk about difficulties going outside due to social anxiety problems, and yet are broadcasting themselves live. It's enough of a barrier for them somehow.
Social anxiety are two different things. Much different, you can have social anxiety and be extrovert. Or be introvert and have none.
How? What's their technique for overcoming the anxiety with a live stream audience?
None of the audience members are in the same room. They're just words on a screen. It's not as "real" in comparison.
Maybe they didn't overcome anything, there are just different sources of anxiety.
There is no control outside; via the stream they control visibility, access, set, and setting. Streams are also heavily one-sided; nothing to throw you off.
The technique is to control everything, basically.