I don't do any ML and don't know much about it, but the Elixir / Phoenix people around José Valim now build ML software (nx, livebook) and I'm excited for this.
So whatever headstart Python might have in machine learning, it is only a matter of time until all major languages support the same C, C++ and Fortran libraries.
The only things holding it, are having anyone that cares enough to write those bindings, and the culture of which languages are accepted when submiting papers.
Once Python got the edge in certain areas - particularly data processing - it was an upward spiral. The same can be said of JavaScript for webdev over Ruby and Python, with its special place at the heart of every browser.
I'm not entirely sure why Python got its initial edge for data processing. I think Google probably played a big role by sponsoring Guido and making it one of the key languages used internally and on App Engine. Ruby also had its share of drama and not everyone appreciates its "More than one way" (TMTOWTDI) philosophy.