Was World War 1 destined to happen or could it have been stopped?

Replace three or four idiots in high places with wise men, and it might have all been very different. These include:

The Czar of Russia. The war would have remained a local one, between the Austro-Hungarians and the Serbs, except that Russia decided to intervene on behalf of Serbia. The Serbians were in the wrong, their intelligence service having backed terrorists who had assassinated the heir to the throne of Austria-Hungary, and his wife. Russia had no alliance, no treaty, no obligation at all to help the Serbs in the catastrophe they had created for themselves, by murdering the next ruler of a neighboring empire fifty times bigger than Serbia. Russia intervened because the Russians had historically seen themselves as the "Mother of the Slavs".

The Kaiser of Germany. He was on his yacht most of July while the crisis was building, having a pleasant cruise in the Baltic. He seems to have given the matter very little thought, but then, he gave few things much deep thought. The Germans had very able and experienced professional diplomats, whose life's work had been German foreign relations. They lived in dread of the Kaiser's occasional forays into foreign affairs, for which some called him "Wilhelm the Sudden". Germany was an ally of Austria-Hungary, and the leaders of that "dual monarchy" sought assurances from Germany that Germany would honor its obligations under their treaty of alliance. Wilhelm thoughtlessly replied with what's called a "blank check", handing the Austrians the power to drag Germany into the war. (Incidentally, the last US president, Bush, sought to give the Georgians a similar blank check, to give the Georgians the power to drag the US into a war on their side against Russia).

The Austrian Foreign Minister, a lying piece of scum. He deliberately misled the Germans and withheld crucial information from them, to insure that the Germans would be fighting beside the Austrians.

Replace just those three with men of wisdom and good will, and the world might be a totally different place today.