Be careful not to write it off too lightly. As far as I can see from the article, the professor did have real world experience, and still got into bad trouble by being overconfident.

Still massively overconfident and un-prepared. Its easy to have "experience" but be lacking in the correct type of experience. Simple examples here: treefall. His previous experience was in the alpine, so maybe he wasn't expecting this? Also, its not clear how much basic experience he had was in the back-country (self-supported). That would seem to explain his lack of basic preperation (re: 10 essentials). Nor is it clear how well he studied his maps--lots of water-crossings--some of these issues should not have been surprises.

Yep. The more general lesson I see to be learned from this story is: never take inherently dangerous activities or situations lightly, even if you've done it a few times before and nothing seemed to go wrong.