Public K-12 education spending increased from 2.3% of American GDP in 1950 to 5.5% of GDP in 2015. [0]

See https://ourworldindata.org/grapher/us-education-expenditure-... (as linked from https://freddiedeboer.substack.com/p/education-commentary-is... )

Educational achievement in the US has been roughly the same as in the 1950s. It seems almost as if public education doesn't matter?

[0] Keep in mind that American real GDP per capital increased enormously over time as well. See https://fred.stlouisfed.org/series/A939RX0Q048SBEA