I don't understand how the average person cannot comprehend this. The point isn't to "hike far, fast"; it's "walk around, hang out in nature, maybe wind up somewhere new." Maybe he wanted to head out, push as far as he was able and willing, and then die. Maybe he was sick and tired of living and working in our shitty society. What's so hard to understand about that? Particularly with the cash he had on hand, which is exactly what I would do: clear out bank accounts and/or max out credit cards with cash advances, and then disappear forever with no expectation of dealing with a financial institution ever again.
The assumption that he must have died purely by accident is absurd; or, if not, that he must have been mentally ill. I could absolutely see myself doing this in another 5-15 years. There's so very little worth living for, but I learned 10 years ago I'm not willing to off myself in the ways people normally do. Heading out into nature and lasting as long as I can on my own seems like the workaround to "being ready to die", but "not willing to hang, shoot, or poison myself".
No, I don't need help. Tried the suicide route 10 years ago (very seriously, not as a call for help), and discovered that I'm not quite that fed up with life yet; and when I am, that's not how I want to go. This story is exactly the kind of method I'd use if the desire to fade from the world resurfaces.