Try it. Point someone at trying to learn programming at sbcl. What percentage do you think have any clue what you just wrote let alone run a debian based distro or even know what that is?
Compare that experience to choosing python. Forget the actual language just all the overhead. It's not a close run thing no matter how angry common lispers get about it.
This is my exact experience of common lisp. People aggressively pretend there's no problem other than other people are stupid and have broken minds because they didn't get functional early enough and so on.
Land of Lisp at least tried, right? And did a vastly better job than anything else I've seen. Couldn't manage to do it all on sbcl though, huh? That's a shame, isn't it? Why do you think the best effort failed in something like that?