Uncertainty, unforeseen surprise
The greater hazard is in the unforeseen, and how we react.
With uncertainty, we, humans remain a hazard to ourselves - how we manage surprise.
This has always been so, but arguably reducing in line with safety tends.
Conversely where most of the easier situational hazards have been identified, those which might be encountered are more likely to be unseen, or discounted with erroneous reasoning, and thus a surprise.
There is increasing need to be prepared to be surprised and consider how we might respond.
Safety discussions (as in posts above) often overlook the urgency in situations which has been considered previously, which is reflected in procedures:
If - Then - Act. There is no need to double think situations, particularly where thinking might be in short supply when surprised.
An emergency descent is based on physiological needs, not traffic density. Beware false reasoning.