==That means that earnings were coming from somewhere, and if not from core consumer products, then presumably from other things that the stock-market-wealthy were buying from each other, at presumably inflating prices, or at least quantities.==

It isn’t a given that you need to increase earnings to increase your P/E ratio. The “E” is your Earning Per Share. Buying back shares lowers your denominator and magically increases EPS, which drives the price higher.