How could you know that? Are you a time traveller? It is unlikely in any specific year, but over 100 years a 1% chance is likely to happen and the risks seem elevated right now. There isn't anything in particular stopping WW3 and there are lots of ways it could happen (open war with Russia, China or Iran spring to mind, civil war in the US spiralling globally is thinkable, the EU is re-arming and something absurd might happen there for a 3rd time). The US doesn't have the economic sway it used to either, it appears unable to just dictate military terms to its competitors right now which has been a major factor for the last 70 years.
Even a good argument isn't comforting. There were really good arguments why WW1 and WW2 wouldn't break out. In the case of WW2 for example, it was pretty foreseeable what could happen - devastation of Europe, probable defeat of the Germans by a large coalition and a roughly century-long occupation. No real upside for them. Happened anyway. And famously before WWI there was that book that correctly argued that the economic interconnections between European powers was so great that war could only bring economic ruin - which also happened to be right in hindsight, WWI set up some of the most catastrophic economic conditions ever seen and was also the death knell of Europe's long term economic dominance.