I just finished Johnny Dankworth's autobio, "Jazz in Revolution" (1998), and came across JD's explanation for why Jazz isn't and will never be popular:
......."jazz is a music for the minority. It can only be truly understood and evaluated by people gifted with 'chordal ears'- IOW, those lucky folk who can listen to the improvisational skills of a soloist and still hear the underlying chord structure. So jazz music can only by luck become popular in the wider sense.,and can rarely enjoy the financial security and mass acclaim which goes with that phenomenon. Thus most jazz musicians remain skilled, dedicated and poor, and even a jazz world-star name like Dizzy Gillespie's was and still is for that matter-unfamiliar to most people in the country of his birth."
He used Diz as an example, because he was working with him at the time, and was a very close friend of his.
This explains a lot.