Because as far as Karkat is concerned, the worst implication of what Sollux is saying is that he's made decisions that will screw other people over, rather than himself, and so that's what he's most offended by – but he does balk at that, his ears flattening against his head.

"No fucking way," he says, but he doesn't sound much like he disbelieves it. He growls in frustration. "Well it obviously wasn't a pinpoint accurate predictor of the future, was it?"