This is something that apparently the US has not been cured of, even after World War II.
I do understand the point that things seemed great for America after the war. And folks want more of that.
Maybe it has something to do with the protestant work ethic, as some folks argue.
But the main reason for US success was unique. Everyone else had had their industry and capital destroyed. The US stood alone as being in good repair and mostly undamaged. Plus it had a massive country to exploit.
So relatively-speaking, life was good.
Now the whole world is in competition. And the game is very different. Indian and Chinese labour, for instance, is much cheaper than US labour. Tough to combat, until robots do everything.