You're damn right this country was great back when we had strong union jobs and a family could live comfortably on a single income. There were strong regulations and the top tax bracket was near 90%. Things weren't great for everyone but at least we weren't fucked like we are now.
Unfortunately, the period you're referring to was an inherently unsustainable one caused by the fact that the US emerged as a victor from a World War, and coincidentally the only one of the major powers in that war whose population and infrastructure were not seriously ravaged by it. Even among the victors - Britain, China, France, let's not even mention the Soviets - all paid a heavy price on their home territory. The losers received economic support from the magnanimous Western powers, but that was cold comfort to a populace largely bombed into ruins.
So the US got to live in a bubble for a decade or two where the rest of the world didn't have the technology or the infrastructure to compete with us in any meaningful economic area. (They either were rebuilding it, never had it in the first place, or were too busy tearing themselves apart in postcolonial revolutions.) As a result, we had near-autarky in an industrial economy buoyed by barely sustainable Cold War military and aerospace spending. Times were good.
But you do get that it was never going to stay that way, right? Eventually the US was going to have to compete with the rest of the world for things. And lo and behold, they could make transistors cheaper in Japan, then they could make automobiles cheaper (and noticeably better!) there, too. Textiles disappeared to Southeast Asia, and steel and other raw materials manufactures moved to Asia as well. By the time the '90s and NAFTA rolled around, it was pretty clear that American consumers would much rather pay a quarter for a can of Coke made in Mexico than 50 cents of one bottled in Virginia. Unless it shut itself off from the world completely - thereby hosing its own exports market - the US could not sustain living wages in low skill jobs forever. The modern equivalent of $55/hour for high school graduates in Detroit who welded three car doors together an hour between smoke breaks was never, ever going to last.