E.g. decentralized services like mastodon, or my own little ARM home server - since there's no profit, I need to squeeze all I can out of that hardware.
This in mind, I tried to build something simple in Crystal and wasted an insane amount of time shaving yaks and gave up. I'm sure I would have finished the project in Ruby in the same amount of time - probably partially because of my familiarity but more because the libraries are so much better.
Why not both?
Though productivity and performance are not the only factors, I could see a time in which a language with similar values to what the Ruby community values but with far better performance reaches parity with the Ruby ecosystem for productivity - that would be interesting.
Maybe this will be Crystal, or maybe Ruby's JIT will catch up, or have the option of compiling to LLVM in the future, who knows?