Regardless of how bad and horrible war is, there is no denying war, especially World War 2 contributed greatly to the advancement of Science, Technology and Medicine. This is because the need to survive and win the war, all countries involved poured unlimited resources into science and technology to develop the best weapons to defeat their enemies.
For example, Nazi Germany gave us Jet Engine and Rockets, USA gave us Atomic Energy, United Kingdom gave us Radar and Computer. The Cold War gave us Satellite, Internet, GPS and many more. Not to mention advanced in medicine because the country with the best medicine are more likely to save their soldier and redeploy them into the battlefield.
There are always two sides to a coin. As the saying goes, there are no good guys or bad guys in a war, only winners and loser. As George Orwell puts it beautifully, “He who controls the past controls the future. He who controls the present controls the past.”