It's true that Python can get as fast as other languages by writing your code in other languages and using Python to call it. This is a selling point if you're almost entirely reusing high-level components. It is not a compelling observation if you have any aspirations to, for instance, create your own algorithms. In that case, you spend a lot of time and effort struggling to express your idea as vector/matrix math so it's fast instead of just writing it. Or you write it in not-Python, and then have the extra hassle of having to wrap it in Python. It works...just okay.