As a perforner (in the UK), very few. As someone who has used their experience and knowledge to gain other work, a few more. Most full-time "folkies" I can think of play in several incarnations, do school's work, sessions work, produce or write music or act. Or in some cases now have a pension to provide backup (and good luck to them).

Making a living solely as a gigging musician, on their own? Vin, er?

Steve