Wars have a way of getting out of hand. A nation may go to war over a fairly realistic goal, only to find itself mired in a conflict it cannot exit that is being escalated by forces beyond its control.

Indeed. This may possibly include trade wars, such as the one taking place now.

Because they refuse to believe that it is an extinction level event (“project fear”); or they think the threat of damage will force their opponent to surrender (“they need us more than we need them”).

It would hardly be the first time that a government failed to understand the situation they found themselves in.

Totally this. Covid-19 really opened my eye on how all governments basically lie to avoid “fear” in public.