WW1 started (among other things) because the "superpowers" in Europe had been arming each other for quite a while in fear of aggression from the other superpowers (not completely unreasonable, given the wars of the previous century). This, in turn, forced the other superpowers to invest more in armaments and army. To top it off, they made treaties of alliance/military intervention (the Triple Alliance and the Triple Entente).

The assassination of the archduke was like flipping a light switch in a house saturated with gas. Austria declares war to Serbia, which is defended by Russia, so Germany has to declare war to Russia; Germany expects France to join Russia so they declare war to France, but their battle plans to conquer France require passing through Belgium. The UK needs Belgium to remain neutral, so they declare war to Germany... and so on. Once the wheels are in motion, and everyone is ready for war, war just happens - whether coke is there or not.

>I always wondered why WW1 started.

For a war to start, you need 3 things: materiel, political support, popular support. In 1914 both the Central Powers and the Entente had all 3 criteria satisfied. The war ended when the Central Powers ran out of popular support for the war.

A man called Archie Duke shot an ostrich because he was hungry.

One can make an excellent argument that WWI started because Germany's last Kaiser - https://en.wikipedia.org/wiki/Wilhelm_II - was a narcissistic, blundering man-child.

(Not to say that any other nation's leaders were models of wisdom and responsibility.)