There is an over representation of open source in the amateur and student communities because open source it's usually free while commercial products are very expensive. It's true however that there is a tendency where open source is displacing more and more commercial products even in commercial settings. I, for example, prefer using python over matlab, even if matlab were free but I'm not very representative since I actually love programming and programming languages and don't mind working with virtualenvs and configuring emacs to my needs. Most engineers and scientists don't have the time or the intestest in learning to do so and prefer a suboptimal (in my opinion) language and more polished tools that Just Work. It's sad that to this day there are incredibly cool libraries like TensorFlow for python and yet there is nothing as easy to use for debugging or profiling as the matlab editor. I know there are alternatives, for example PyCharm, but I assure you that most non-software engineers are not willing to use "such complex" tools.