Because they thought they were going to hit a tree and probably misjudged how much space they had.
Fines and possible jail time for negligence and/or careless driving may well be in order, but the fact of the matter is, it was an accident. Born out of a massive error in judgement as you say. It's not a "so-called" accident, because that suggests it was deliberate but dressed up to look like an accident. No, it was an accident. It was reckless, it was stupid, and it was negligent, which is what any legal action should focus on.