This thread should be stickied because of the great information herein!
It sounds like whoever taught this guy hadn't drilled him enough about aeronautical decision making and risk management. Sadly I have met more than one CFI who didn't know much about the Fundamentals of Instructing like the Law of Primacy.
Or maybe he was taught well initially, but after he earned his certificate(s) he became so complacent over time (10,000 hours of GA flying? wow!) that his sense of invulnerability grew out of control. Well, that sucks either way, but if the guy wasn't willing to spend the time rectifying his bad habits, then he shouldn't fly at all.