I prefer sessions to concerts, the best ones have been spontaneous----and some of the most memorable ones have been when some old singer, perhaps a Traveller, shares a song they learned by ear as past of the carrying stream of tradition; for me this is like a gold nugget straight from the earth -- maybe learned round a campfire, or at a grandmothers knee. History, reality -- a gift, a treasure.
It is not the quality of the person's singing but the sense of awe that this song has been handed down, shared over years - and you will continue the process.
I do not judge a singer by how 'good' the performance is - if they are the only person left who knows and sings that song -- they have a duty to keep it alive, pass it on!
And yes I do sometimes pay to attend concerts - and I like the performers am getting older, so I accept that the aging process has affected them too and I enjoy the memories and appreciate the fact that they - and I - are still here and able to enjoy the music!