Hikers who disappear in the wilderness

Solo hikers going off-trail in the wilderness are vulnerable to disappearing. Some are never found:

NYT: Lost in the Beartooth Mountains

...Hiking in true wilderness on trails with a companion is mildly risky -- probably comparable to bicycle commuting. Hiking off trail with a companion is risky -- maybe more like motorcycle touring or parachuting. Hiking off trail alone in rugged country is very risky -- I'd guess comparable to hang gliding or mountain climbing with companions. That doesn't mean people shouldn't do it, but it's important that they understand and weigh risks appropriately. In Brian's case the decision of the BC government to remove hiker logs from the trailheads made his solo off-trail hike even more risky than he could have planned on