Bernard:
       Oh, I suppose if I was doing one or two gigs per year, I could get into promoting but that's not what I'm up to. Folk venues are limited, as are the funds available to both the organizers and entertainers. Folk is by comparison to other genres, not very lucrative.
Others have suggested that even professional folk singers have to find other jobs. For me, this means playing in the "Hospitality" industry.   i.e. Pubs & Restaurants where you have to accommodate the needs of the business as well as the patrons.
Over the years "Hospitality" has become the mainstay and true folk venues are a real treat when I can fit them in.
I have a great deal of respect for anyone who chooses to run a folk club or festival. They are not going to get rich doing it and I believe, get seriously gouged by many of the big names.
So I give them a break when I can but working for a percentage is pretty well out of the question, for the reason I stated earlier.