Not everything, but languages do serve a purpose tied to how many (and which) people speak them, and that's true for general purpose programming languages in the same way as for human languages. If learning Klingon is someone's "thing" then, well, everyone can judge for themselves whether the predicate "true weirdo" applies or not, but it's descriptive enough.
I would disagree, purely because the utility of a programming language doesn’t hinge on how many speak it.
The goal of programming languages is to execute instructions on the machine. Brainfuck still executes machine code the same whether 2 people write it or it becomes the lingua Franca of AI. There’s fewer libraries, but C FFI bridges a lot of that.
Learning Klingon is odd because human languages are meant for communication, so a language with no speakers is largely pointless (barring cultural value, which Klingon largely lacks because it’s a fictitious language and too modern to have that niche coolness).
> The goal of programming languages is to execute instructions on the machine.
The goal of a general purpose programming language is to communicate a program from one human to another, and from one human today to the same human tomorrow, while understanding that a program is only written once, but read many times. -- In that goal it is no different from a natural language. -- This goal needs to be optimized for within the constraint that programs must also compile and execute in the way and with the outcomes that a human reading the code would expect.
Your observation about Brainfuck makes my point for me: If the execution was the actual goal, then Brainfuck would be as good a programming language as Rust, Zig, or Nim; but that clearly isn't the case.