I read an interview of Werner Herzog, who directed the documentary. He seems to be fascinated with people whose outsized dreams inspire them to try superhuman tasks.
It's easy to dismiss someone who would get that close to grizzlies as demented. I haven't seen the documentary but what's intriguing is that Tim sounds like a guy who was trying to achieve something noble with his life. I want to believe it wasn't soley a fame-and-status trip. Another element that appeals to me was that the guy pulled himself out of a deep hole of drug and alcohol abuse.
So Tim stikes me as a man with restlessness or energy that just won't allow him to lead a humdrum existence. The easiest route is to give in to self-destructive behavior. The tougher way is to direct those urges to a pursuit that gives you a high-wire thrill, but is altrustic. So, as misguided as his methods may have been, I can't help but feel empathy for him.
I also found Herzog's view of Nature of interest. It's not hostile or benign. It's simply there. Attempts to assign romantic interpretations to Nature are dangerous delusions. Anway, I can't wait to see the movie!