My two season-ending injuries did not involve any of the things people are discussing here: no exhaustion, no skiing at the edge of my capabilities, no excessively high speed, no crowded slopes, and no skiing at the edge of a trail. Both injuries were, as far as I can tell, unpredictable quirks caused by unpreventable factors. Neither could have been avoided by me being more prepared.
#1: I was skiing round turns, short radius, in soft buttery spring snow, first tracks down a green groomer. My ski folded (no reason, just did), throwing me over the handle bars and upside down. I slid into the woods, facing up, head first. Came to an abrupt stop on a boulder. I'm lucky I did not hit on my neck or spine, or head. The impact was directly on my right scapula, which splintered, and my right clavicle folded and broke. That right shoulder has mended up quite cleanly. Ligaments were not torn, thankfully. And I am alive, not paralyzed from the neck down. That easily could have happened.
#2: I was skiing bumps in spring snow in a boulder-filled twisty turny narrow trail. I was moving down at a snail's pace, carefully choosing my line to avoid messing up my edges on granite ledges. At one point I traversed to find a line, going oh probably 0.005 mph. My intended path was up and over a medium-sized bump while I searched below for a clean path down the hill. One ski went up and over the bump, but the other penetrated the bump's soft side and came to an abrupt stop. This threw me downhill onto the next bump, where I landed upside down at very, very slow speed on the top of my right shoulder. This was a hard abrupt landing, no sliding, just a blunt stoppage, which resulted in a broken humerus. That right shoulder has again mended up quite cleanly. There was no ligament damage, thankfully. I skied down, rode the chair up, and skied that run again just to let it know I was the boss. No pole plants, though. That second run I did not traverse.
So none of the usual risk management behaviors, avoiding being in the back seat, getting more strong and fit, quitting earlier in the day before fatigue sets in, minding my speed, staying away from crowded slopes, avoiding trail edges, or simply skiing smarter would have kept me safe (as far as I can tell).
My take-away: Skiing is inherently dangerous. I'll do what makes me happy as long as I'm willing to accept that unpreventable major injuries can happen with no warning. I constantly ask myself, if I lose control right now because of some unexpected anomaly, am I willing to take the consequences? I wish I didn't ask myself that. Caution infects my enthusiasm.