A lot of poetry readers are snobs who will only read verse which bears the imprimatur of establishment venues.
Living as I do on a Social Security budget, I can't afford to place advertisements for my books in prestigious periodicals like American Poetry Review or Fence or the Yale Review et al.
Hence most of the poetry-reading public doesn't even know that my books exist and that they can be downloaded free as PDFs and/or bought inexpensively in paperback editions (I always set my "profit" at zero when I prep the books).
Many poets have websites or blogs where they promote their own mostly deadtree publications and those of their friends, but few if any of these poets ever mention the availability of my "vanity" volumes because my publishing activity constitutes a threat to the economy of their supposedly legitimate practice.
I think a lot of poets are really angry at me for giving my books away free, and that they engage in a conspiracy of silence regarding my publications.
And of course, none of my available-for-free books has ever been reviewed (or even listed, for that matter) by any online webzine or poetry site. They pretend I don't exist.
And who knows, maybe they're right. If nobody notes that my books exist, then I guess they don't exist.