250' drop, +/-7 rollovers, no seatbelt, chance witnesses with medical training... lucky is an understatement.
I came away from reading this article with mixed feelings. I'm going to play the devil's advocate here, so please keep that in mind as I'm only attempting to explore the root cause and contributing factors.
I think articles like this are good reminders for some, and a discouragement to others. One of the final statements was "A good piece of advice he’ll follow while off-roading alone in the future: Turn around once the road gets to a point when you need to switch gears into 4-low." I think it's worth noting that most of us are just getting started when the transfer case is shifted into low range, so if you're new to overlanding don't take this is an absolute indicator you need to turn around.
Without being a witness or knowing the individual involved it's hard to say what the detailed reasons were for the accident, but let's take it at face value and throw in just a few assumptions for conversation sake.
1) "James Scully was heading up to the Castle Peak and Conundrum Peak trailhead outside of Aspen and said he wanted to get to as high a campground as possible before starting his hike early the next morning. His quest to save his legs from several hundred feet of hiking nearly cost him his life."
Minor point here, but if you're already going to go on a hike up a mountain... what's a few hundred feet extra? It's like driving around the gym parking lot for 30 minutes waiting to get a parking spot closer to the door... only to go inside and run on a treadmill for 5 miles.
2) "Scully was on Forest Road 102 and passed two Denver men, both 19-year-old students at the University of Colorado, in a Jeep Wrangler before quickly approaching a tricky switchback on the four-wheel drive road."
It says he passed another vehicle while "quickly" approaching a switchback. If you've been on many mountain side trails, you know there's not many places to pass, much less "quickly". I'm going to assume he was in a hurry and maybe had a touch of ego encouraging him to get ahead of the witnesses.
3) "The driver of the Jeep, Parker Tinsley, got out to talk to Scully about how to maneuver through the switchback, which was a thin spot with a big snowfield, said the Jeep’s passenger Ben Crabb."
Points to the driver for stopping to inspect the obstacle here. This might have been an indicator that one should turn around, but it's possible the presence of other individuals encouraged the driver to take on a challenge slightly beyond his comfort level.
4) “He eventually got his (FJ Cruiser) up it,” Crabb said. “We started placing rocks on the snow for traction and then we got up that part.”
I'm assuming from the comment that the FJ driver didn't prep the trail, but the Jeep drivers recognized the necessity before proceeding. This might have been a spot to use traction mats for extra assurance if someone had a set.
5) "But that turn was just the beginning. Not much farther up the road, Tinsley and Crabb watched Scully attempt to cross another narrow section of road covered in snow, but this time there was a “harrowing exposure on the left,” Crabb said. Crabb and Tinsley watched as Scully tried to drive through the snow. As soon as I saw it, I thought it was really sketchy, Crabb said."
"Scully said he didn’t think much about the snowbank, because while the dry part of the road was narrow, he figured he would just drive through the snow without incident. His FJ Cruiser was modified for off-roading with a 6-inch lift, 35-inch tires and a snorkel for driving through water, he said."
Again, without being there it's hard to determine the "sketchiness" of the obstacle but if it was apparent to the guys in the Jeep, then it probably would have warranted a closer look before proceeding.
6) Tinsley and Crabb were parked about 40 feet behind as they watched Scully try to throttle over the snow.
Key point here; the FJ driver was attempting to throttle over the snow. When you have a dangerous drop-off near an obstacle on a trail, "throttling" over it greatly increases the chance that once you get "bite" on a surface, you could very well be headed in the wrong direction as the vehicle pivots in the direction of traction. If your foot has the pedal on the floor... your floor may quickly become your ceiling.