You're both wrong. Many people subscribed to each belief.
The economists, globalists and industry people believed that it could never happen. The military, nationalist and political folks figured it would be inevitable, or at very least if it happened they had to win.
Many people subscribed to the argument of the economists and globalists in more democratic countries because it was a comforting illusion the people in the more militaristic autocracies, believed it was inevitable, and incidentally were the nations that hold the most culpability for WW1, Germany, Russia, Austro-Hungarian empire.
Wait a minute why is all of my description starting to sound terribly and horribly familiar to what is going on now?
Seriously those that will continue to posist that war will not come are foolish and don't realizing that the first steps are already in progress with the information war being waged right now through cyberspace.
Note I don't want a war to happen and think it will be horrible and terrible, but all the elements are in place for it to happen. A shifting balance of power into a multipolar world, multiple nations either facing decline or ascendancy, realpolitik becoming the norm in international relations, it all looks very grim unless some very wise, peace loving and capable leaders emerge on the world stage soon.