There is a saying that goes among mountaineers, ‘Climbing Everest requires condition. Climbing K2, though, it requires heart.’
Because of the general shape of K2, it is much harder than climbing Everest. When climbing Everest, mountaineers generally prefer the back side of it, entering from the Gate. Everest is not symmetrical, so it provides two preferences, North Face being generally harder.
K2, is symmetrical. Climbing angle of K2 is higher, and avalanches occur more often. It doesn’t have a backdoor (Pakistani side is easier but it’s not drastically different from the other side). K2 is savage. It doesn’t even have a cool name like the others. It’s cold, strict, and, well, satanic.
Also, since it is way more famous than K2 as the tallest on Earth, more people wanted to climb it, and more advanced installments were made to the climbing of Everest.
Some also call it the ‘Runner Up Syndrome’. Being the second is way harsher than being the third. You feel you could’ve gotten the prize, and that you were just so close, so you are way more furious. Hell, K2 is furious.