Pyston was better supported, but I think just too ambitious - IIRC it was initially intended to be a full rewrite and to be compatible with C-extensions.
You have a point though, no company can replace javascript , the cost is straightly forbidden. But Python as mainly a backend language at the time, it can be more realistically replaced, with newer more performant alternatives like Golang, and to some extent node.js.
But it has its own stronghold, which is data/ml land stuff. However, that community has gotten around with Python in its own way, either they are tolering the slowness because that happens behind the scene, or they are bypassing the performance bottleneck to c-extensions.
So in the end, I guess people love complaining about Python's performance, including myself, but it never reaches the break point where they said enough is enough.