There are a very few that are making a comfortable living at singing folk music.
Many are doing songs they've written themselves or branching out into other kinds
of material, jazz songs, classical etc.

I think the day of Burl Ives has ended. The shows have gotten too big and commercialized.
Dry ice, flashing lights dominate. Not many are interested in listening to a good song unadorned with high production techniques.

There will be those however who are endowed with a gift to entertain and have an aura
of charisma. We know who they are. I don't know how much this can be developed.

I suspect that in the UK scene, there is not a lot or even a comfortable amount of money to
be made. Listening to Child ballads is not a usual crowd pleaser.

There are those in the States who have a huge production budget comparatively. Joan Baez and Leonard Cohen bring a full blown "show" with their acts. (This is assuming that both of these performers could be called folk singers any more).

Audiences seem to cheer those who with clever stage patter or can tear it up with
virtuoso instrumental ability. Just an unadorned song doesn't cut it any more.

A lot of this has to do with what is called "entertainment" these days. Personally, I find
that a lot of the big ticket concerts are not interesting to me. Also too expensive.
I don't frequent clubs or places that permit smoking. I prefer having people in my home to share music or jamming jazz with my buddies. I think many people share this view and this is why folk concerts are on the wane.

The solution (at the risk of being redundant) is to hone your craft the best you can. Voice lessons, acting lessons, writing skills for patter, research on folk material, even movement classes can help you here.

As Naomi Klein describes her mother's mode of apparel, I think the same adjective can apply to many "folkies". The word is "schlumpy". (Good Yiddishism, I think).