How do professional folk musicians make a living?

Brian Peters is probably the best one to answer this, but I suspect that for most it is from fees for live performance, teaching, sales of CDs etc rather than from intellectual rights from their compositions or arrangements.

I disagree with Jim about the significance of professionals. My first contact with folk music was not from amateurs, either revival or traditional, but from professional performances on TV and radio, which led me into the largely amateur folk clubs, and very much later into 'authentic' traditional music. The effect professionals have on the amateur scene, through introducing songs and tunes into the wider repertoire, composing tunes and arrangements, and developing and teaching techniques and musical styles should not be underestimated. Of course, good amateurs and semi-professionals contribute to this as well, but their impact is often less widespread. The amateur folk scene would undoubtedly continue without the professionals, but whether it would flourish to the same extent is another matter.