Well, let me just say that my statement is most definitely still incompatible with yours: the YPG/J are one of the most well-trained, disciplined, and professio

Well, let me just say that my statement is most definitely still incompatible with yours: the YPG/J are one of the most well-trained, disciplined, and professional army in the entirety of the Middle East. Yes, they rival that of the IRGC in Iran and the TSK in Turkey, but not quite on the level IDF in Israel. Their only shortcoming is the lack of heavy weaponry and high-tech training. That kind of specialty requires special connections or domestic heavy industry. How did they become so effective? I would put it as two parts: 1) do-or-die as you said, and 2) rich history of duty, service, and honor. The former is pure grit and there is no shortage of that on the radical Islamist side of things but the latter requires a personal and social investment that is far more rare.