I believe Steven Stapleton, David Tibet and some of the members of Throbbing Gristle may be better off than most. They've been doing it for so long, it's almost hard to believe they haven't accumulated some sort of wealth.
David Tibet aka Current 93 has been releasing "subscription series" for the past five years and they are all sold out before it's even pressed. David is also doing art and making money this way.
I've heard yes / no when it comes to the Legendary Pink Dots. They've had so many re-releases and tours over the years. I remember Edward being asked one time about a Tear Garden tour and he responded saying the plan was to hold off on that until the money was really needed. Of course, no Tear Garden tour has ever occurred.
And John Cage isn't a "mondern noise artist." - atsonicpark