“Ruby is just for web development!”
You can do a heck of a lot with Ruby other than web development. Ruby is a great choice for plenty of software, like…
Package managers like Homebrew. Local deployment configurations like Vagrant and infrastructure management tools like Puppet or Chef. Hey, why don’t you write something like Fastlane to automate huge swathes of your mobile app deployment pipeline?
Shoes helps you build GUI applications for the desktop.
You can make games in Ruby using tools like Gosu or DragonRuby, and Ruby is used as the plugin language for some versions of the popular RPG Maker engine.
Metasploit modules are written in Ruby.
Drop beats with Sonic Pi.