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I disagree with your assumptions. While our stocks of natural resources may possibly (but not definitively) be lower than before the Great Depression, we are unequivocally more wealthy now than we were then.
Ignoring our increases in intellectual and human capital is to ignore vital parts of the equation.
We generate much more GDP now with each barrel of oil or ton of steel than we did even 20 years ago.
This doesn't mean that we have no risk of a new depression, but I note that Leonard has long shown himself to be a far from objective observer of the economic pot he tries to stir.