Not really a fan of militarism, but WWII had a lot of people working alongside a lot of other people they wouldn't usually spend time with. And a desperate need to innovate new technology and new industrial and managerial processes. So there was unity in the face of a common threat.
Also, GI Bills allowed intelligent individuals to get an education without worrying about debt as well as discounted mortgages and business loans.
That need dissipated after the 60s and there was more emphasis on hedonism and competitive individual ambition. Then in the 80s competitive economic individualism started to dominate everything else.
The result was a classic race to the bottom - with a few extreme winners who are indulged and beatified, a productive but often hamstrung professional underclass, and a huge precariat of economic losers.
At the same time the media landscape started promoting division and tribalism for profit.
So now we have a dysfunctional culture which is unable to cope with challenges like Covid, gun violence, and climate catastrophe because it has been groomed to be more emotional than rational, and the tone has affected everyone from the top down.