Lopsang Jangbu is the LeBron James of the climbing world. Dude's a savant: "although he'd only been climbing for three years […] he'd […] established a reputation as a high-altitude mountaineer of the highest caliber" (9.39). Fancy, right?
Unfortunately, this immense talent may cause him to overextend himself during the 1996 climbing season. First he makes the decision to climb the mountain without bottled oxygen, which places a greater strain on his mental and physical faculties, and then he decides to assist in Sandy Pittman's ascent, pulling her up the mountain using his own power. This takes a pretty big toll on his body: Krakauer observes the usually stoic Sherpa puking his guts out as he approaches the summit.
That doesn't mean Lopsang deserves any blame for the disaster—he's as much a victim as anyone. Lopsang and Scott Fischer are extremely close, so the young guide is understandably devastated when Fischer dies. To make things even sadder (if that's possible), Lopsang dies in an avalanche just months after surviving the disaster. In the end, it doesn't necessarily matter how skilled you are—it's all just a roll of the dice when you're on Everest.