Miramonti is criticizing the media that seems to only understand that Prince is known for like, 3 hits that are ~3 decades old.
I think?
A lot of this perceived gap in Prince's output that seems to be inversely correlated to his extreme, seemingly "underground" popularity is probably due to how strongly he has guarded his image and his property. You won't find him in any of the sources that most of the kids today use for music. He long ago abandoned the video and pure commercial aspects of the industry as he's been fighting his own little war against the music industry and all others trying to license his name (all of that "The Artist" stuff). That is not to say that he isn't commercial with all of his staging and crafted image, that's just part of his package.
What his has done for him has allowed him to maintain strict licensing control of everything that he puts out. Considering his icon status among fans and nearly every musician anywhere, this = $$$.
I remember reading recently that the Stones are worth something like $300 million, or at least Jagger is. Consider that they still tour off and on and have their shit everywhere and can be found in nearly in catalogue, on youtube, wherever.
Apparently, Prince's fortune was reported the other day at ~$330million. About the same as Jagger, with far less public presence, and certainly far, far less hits than the Stones.
But Prince hasn't disappeared. He was always a rather public figure around Minneapolis and toured regularly, including very small gigs and free shows at his compound, I think? That kind of power and control, you can basically do whatever the fuck you want and for Prince, it seemed to be hanging around and playing music all day long with various people. He seemed to be insanely prolific and if the rumors are true, his unheard vault would mean that everything that is known about him really is the tip of the iceberg. He was a true performer, which you don't really see much of these days with musicians.