SP500 price/sales ratio is at the same level as it was last time during dot-com-bubble. The aftermath between 2000 and 2009 was the all-time worst decade for SP500. Total ROI -9 percent, worse than during the 1930s Great Depression.

Combine debt-for-buybacks with the shadow margins and there is potential for quick crash.

similarly with Trump's tax cuts which largely did not end up in pay rises or investment.