BAZOOKA, not A-Bomb or V-2, most important new weapon of WWII

Because the Great Imperial Powers who began and fought WWII had done so under the mantra that "bigger is better", they were hardly shaken by the emergence (near the war's end) of the A-Bomb and the V-2, surely two of the biggest, most expensive and complex weapons systems ever built up to then.

For the emergence of these style of  weapons merely supported their post-1945 expectations of eternal dominance over other smaller nations and over their own colonies and subservient satellites.

With 20/20 hindsight, they should have been much more worried about other much smaller, much cheaper, much simpler weapons that emerged out of WWII : like the bazooka , above all.