Many of today's popular programming languages are free. Java, C#, Python, OCaml, C, Rust.
Why aren't there more non-free, paid, programming languages today?
I ask because Pascal, BASIC, and C++ have always been free languages, in the sense of not proprietary. There also have always been both free and nonfree compilers and interpreters for them, as there are now.
The language being "free" and the compiler/interpreter being "free" are two different things.
Your compiler provider goes bust, compiler is no longer updated but you want to continue to maintain and build your product.
Also, learning it as a child or student almost invariably requires pirating the compiler. Been there, done that.
Building on open and free platforms is just so much better. No need to pirate, and always a way to maintain what you've built.