1945 saw the first horrific use of nuclear weapons on the populace.

The world started to see via radio and tv broadcasting events worldwide.

Communism was feared by Western Society.

The opposed super powers were in fear of each other's military advances. The introduction of the ultra horific Hydrogen Bomb became a reality.

There has always been the ups and downs of a man made economy and employment vs. unemployment

New diseases,getting control of existing diseases added fear.

Crime increased, morals decreased as a result of WWII.

I'm sure there are other valid reasons.