Amateur? Professional?
I suspect you're trying to imply that Linux is written largely by hobbyists, with a low level of skill.
In fact, the standard of its developers is high, and many (probably most: http://www.infoworld.com/article/2610207/open-source-software/who-writes-linux--corporations--more-than-ever.html says 80% of kernel patches) are employed to work on it. And many who aren't paid to work on it will be people who are paid to work on some other software.
Not that the correlation between being paid to work at something, and being good at it, is perfect anyway.
Biting the hand that feeds IT
