Panic selling on financial market,food hoarding and witch hunting are some well known cases of group madness.
But the world wars are similar ?
After all first world war started with a small conflict between Austria and Serbia and ended with all Europe in flames.
All activities above have 2 things in common:
1. The actors don't comunicate
2. Their actions try to avoid a loss, and they try to pass that loss on other actors.
In sort it is a null sum game.
In case of shares, if 2 actors agree not to sell shares, the one who cheats will gain by selling at a better price.
Both they have interest to sell fast their shares.
In case of war, the one who cheats the armistice gains unless it can be punished.
In case of wars the actors try to finish fast their conflict. The intensity and scale of war affects security of other actors who decide to intervine now rather than later when they will be alone
Germany in WW1 was a threat for security stability so British empire had to contain it. Also invasion of Belgium was a dumb thing done by Germans. British empire being obliged by the treaties to intervine..
Because of powerfully economical connections between US and British empire, the German adventure threatened US security, and it was dragged in war.
Now with so much interconnection, further and further countries will be dragged in this war. Not with troops , despite mercenaries been recruited from Latin America and Middle East,but economically.