Isn't "performing" or "putting on a performance" a different thing from "show business"?
When you get up (or sit down or whatever) to perform you step into a certain frame. This even happens telling a joke or an anecdote in casual conversation.
To me, "show business" = performance + Commerce. 'Folk music' continues to be a huge commercial genre, but traditional folk music or informal 'folk club' music has nothing like the same degree of commerciality, though it of course involves 'performance'. So I don't think it's all showbiz.