Growth has happened precisely because net private investment has been declining since 1919 and because consumer expenditures have, meanwhile, been increasing. In theory, the Great Depression was a financial meltdown first caused, and then cured, by central bankers. In fact, the underlying cause of this disaster wasn’t a short-term credit contraction engineered by bankers. The underlying cause of the Great Depression was a fundamental shift of income shares away from wages and consumption to corporate profits, which produced a tidal wave of surplus capital that couldn’t be profitably invested in goods production -- and wasn’t invested in goods production.
In terms of classical, neoclassical, and supply side theory, this shift should have produced more investment and more jobs, but it didn’t. Paying attention to historical evidence allows us to debunk the myth of private investment and explain why the redistribution of income has become the condition of renewed, balanced growth. Doing so lets us see that public-sector incentives to private investment -- say, tax cuts on capital gains or corporate profits -- are not only unnecessary to drive economic growth; they also create tidal waves of surplus capital with no place to go except speculative bubbles that cause crises on the scale of the Great Depression and the recent catastrophe.
To simply cast contemporary US school reform as a speculative bubble gets convoluted, since the investors mostly aren't looking for financial return. However, I have no doubt that the phenomenon is a direct result of the "tidal wave of surplus capital" looking for someplace to be spent.