One thing that I think has been overlooked here (except for in the context of what Terry mentions) is the audience-
Here, in the good old USA, the mass audiences have a consistant tendency to embrace, deify, and then abandon artists and musical genres--
The folk music scare of the 50's and 60's being an good example--if you dig out your Billboard hot Albums chart, you will note that still in the top ranks of all time best sellers are a a few by the Kingston Trio, though they might not have been the most authentic, they were the crest of a wave that carried the full range of folk related entertainers, from Bob Dylan to Jean Ritchie, into the public spotlight.
There were hoots and coffeehouses on every campus, and folk programs on all the major radio stations, even the clean channel 50,000 watters--Obscure old folksongs topped the charts, as well as hot new fakesongs, most important, there were folksingers and folksongs on prime time TV--
And then it all went boom, maybe even faster than it happened(probably way faster, because it had really broken into the pop world with the work of the Weavers)
Now some will say that it was political, and talk about the battles that the Smothers Brothers had with the networks, or mention the sanitization of folk music that occured in connection with "Hootenanny!", but the truth is that the audience walked away, just like it had walked away from so many other wonderful chapters of American music--
There was, for instance, a prom night in about 1956, when every sax player in every jazz combo in America suddenly was unemployed, because kids wanted rock'n'roll and not those pop standards that they'd danced to for more than a generation--
And there were those three Ed Sullivan shows, back in 1964, when Don and Phil, Elvis and Roy, Jerry Lee, and every other American Rocker got bumped off the charts by John, Paul George, and Ringo, and a dozen other of what were often called "British Invaders"--
As always, I have probably gone on way to long with this point, but still the point must be considered--how can you survive, as a musician, an artist, and the active bearer of a tradtion, the when the audience is only with you for a short time, and then, without warning, just disappears? And how can the art form survive?