Common Lisp may be old, but it is extremely powerful relative to Clojure IMO. Clojure startup times are awful, it takes a very opinionated approach to programming (immutable data), its debugger is buggy, it produces unsightly error messages.
Sure, these problems may be fixed, but for me, I want a powerful tool that I can use now.
I've tried several new hot languages at the time (Rust, Dart, Clojure, Go).
I have come to a point in my career where I want to stick to highly complex, but slightly dusty artifacts defined by a standard( C++ & ANSI Common Lisp).
The SBCL implementation of common lisp does not give me all of the headaches of Clojure. I also don't have to restart the repl to load libs.
On using another dynamic language that isn't a lisp... Forget about it.
...Python maybe for machine learning, but I will probably just wrap cafe in CL or something.
PS. I am 25. Seems relevant to this discussion.