...Åke Ohlmarks, became thoroughly disillusioned and warned against its power to seduce youngsters into believing all that fantasy crap was real.
Not without reason: He was being stalked for years by some whacko who called himself "Gandalf" or "Aragorn" or something, and apparently sincerely believed he *was* that character (whichever one it was) from the books.
And this wasn't a case of an isolated nut-job, either -- "Aragalf" was only the leader of a whole "cult" of similar weirdoes. Ohlmarks had to get police protection, IIRC.