Because people don't write C++ or Java or Python "success stories". When someone ships an app in Lisp, they blog about it and it gets posted here. If Lisp were widely used, it would not be newsworthy.
I don't think you hear much about the 'real' Lisp apps. I have for example never seen anything about Amazon's use of Lisp. But they use it. Did you ever read something about the applications that schedule airport operations? Or did you ever hear about SISCOG's software ( http://www.siscog.com/ ) who develop most of their software in Lisp? Their products are used to schedule the crews of public transport systems (trains) in major cities and states.
