In a universe both deprived of any transcendental code of justice and exposed to violence, everybody has reason to fear the worst. The difference between a projection of one's own paranoia and an objective evaluation of circumstances has been worn away.
Rene Girard Violence and the Sacred
When there are no rules, no authority but violence thinking twice is deadly, preemptive strike as response to the slightest signal of hostility is prudent, there is no time for deliberation. It is either you kill our you are killed.
It is striking how some of our online behaviour repeats this basic pattern. It is not, as it is often explained, that people exagerate emotion in text, it is rather that in some circumstances people start to act as if in the middle of a violent conflict. They don't exaggerate negative opinions, they actively seek anything that can be interpreted as hostile and don't wait for any explanation but retaliate. Of course the other side does the same - this is the nature of a flamewar.
The circumstances change - but human nature stays the same and we still carry in our psyche the most primitive programs. They only need a trigger.