FWIW - Prog rock success, for those of us who love it, write it and play it, is as far removed from album sales as possible. Generally, prog bands who sell well (like Yes did starting with 90125, or Genesis post-Duke) do so by sounding, well, highly un-prog. Not necessarily bad, but just not prog. In the case of Rush, Genesis and Yes, to me, it went epically bad (making them very UNsuccessful to my ears and tastes).
I'm glad artists sell records, go gold and platinum and multi-platinum, but that's not why I personally consider a band a success or not, and certainly has NO bearing whether or not I listen/play or otherwise support them.