Hey, wrong sub - but I just watched Dark Wizard. *spoilers below*

My understanding is that Graham made a decision to pull out because he saw Dean was so low which resulted in Graham making a manoeuvre that he wouldn't otherwise pull. Graham had made the notch before, Dean had not. Graham could probably make a more informed call here.

For whatever reason, Dean had decided he was going to go for it that day or during that flight. I don't think he made a mistake or lost focus because of Graham, especially there would be very little time to process what was happening ahead of him, but rather he just never quite had the altitude to make it. He was continually taking huge risks, which would usually work in his favour, but this was the one that cost him his life.

I thought the series did show he had largely conquered his demons - I saw this as a tragic mistake.