One of the great securities of stamp collecting and investing is the wealth of philatelic literature that guarantees a solid interest in our hobby will continue through time.
Sure, most collectors are happy to acquire their stamps and put them in their albums, with the most exposure to philatelic lit being info from one of the stamps newspapers (Linn's) or magazines (Gibbons Stamp Monthly) or a newsletter from a postal agency. Especially topical stamp collectors, with the subject of the stamp more important than arcane catalog information can find much enjoyment with nothing more than the topical information published by the American Topical Association and a few other publications that feature their collecting area.
But those who invest in stamps are happy to know that there is a long and proud tradition of philatelic publishers. It is one of those things that indicate that our long running hobby (172 years; but who's counting?) will be around when collectible areas like Beanie Babies and Pogs are forgotten.