Great developers are curious.
Curriosity leads to inspiration. José Valim, creator of Elxixir, read Seven Languages in Seven Weeks and used those langauges for inspiration for Elixir. Evan Chaplicki drew heavily on ML for Elm inspiration. Joe Armstrong and the Erlang team based initial versions of Erlang on Prolog, and Robert Verding from the same team has built another inspired language, Lisp-Flavored-Erlang. You don't need to be a language designer. You'll get inspired too.