The biggest growth period in the Western world - after WWII - happened to coincide with enthusiastic social spending programs, aggressive government funding of new R&D, and very high tax rates.
In the US the rate peaked at 91% on earnings over $400k - which is about $4m adjusted.
I often see the arguments made about how the US didn't suffer from the 90% tax rate. Those same arguments universally and intentionally ignore the elephant in the room: the US was the prime industrial power left standing in pristine shape after WW2 and largely inherited the globe accordingly. The US stepped right into being globally dominate in manufacturing, which produced a temporary, artificial prop for the middle class of gigantic proportions. That can't be repeated today and it wasn't the high tax rate that helped make things so great for the middle class.
This is also why middle class tax rates are so high in Nordic countries, and most affluent nations with good social welfare structures. Taxing the rich isn't nearly enough. The US would have to shift to a much higher tax system for everyone, and the US middle class (which is spoiled by relatively low income tax rates) will not go for it (not yet anyway).
In the US the rate peaked at 91% on earnings over $400k - which is about $4m adjusted.