Others already pointed out the AI winter. Reading about the history of lisp is very interesting, it almost feels like you are reading about a lost civilization,

Others already pointed out the AI winter. Reading about the history of lisp is very interesting, it almost feels like you are reading about a lost civilization, so ahead of its time. On the other hand, the AI winter is in the past, why isn't lisp used NOW? I think its getting better, the scheme people are working on sorting out their issues, and of course theres Racket, which is awesome. You have the clojure people attracting a lot of java and ruby developers(among others) to at least give lisp a chance. And even the Common Lisp world is on the rise. The biggest problem IMHO is that there are too many non lisp programmers with strong opinions on lisp that spread FUD, even though all their lisp experience can be summarized as "read a scheme tutorial, and wrote a recursive factorial function".