Trickle down economics is a lie. Quantitative easing is so far removed from salaries. It ends up just creating more capital for banks, which they invest into assets (companies and properties being two asset classes) or use as liquidity. Labor isn’t really in the picture at all except that companies which use less of it can be better assets to invest in.

The Fed's interest on excess reserves (IOER) keeps a lot of money there. The graph https://fred.stlouisfed.org/graph/?g=pB2X shows that the IOER was regularly above the effective federal funds rate.

That means, banks made more money parking their money at the Fed, effectively removing it from circulation; than they could make holding bonds.

When a bank holds a government bond, someone else in the economy has to do something with the money they paid for the bond.

In contrast, excess reserves might as well not exist as far as the rest of the economy is concerned.

https://fred.stlouisfed.org/graph/?g=pB2X shows the absolute amount of excess reserves.

IOER explains a big part of the puzzle you found without invoking any conspiracy theories or sly remarks about 'trickle down economics'.

See https://www.cato.org/publications/working-paper/floored-how-... for a broader discussion.

The Feds interest on excess reserves kept the money out of circulation.

If you are starting a business/expanding ops etc it's not complicated to raise cash today.

Could this be a consequence of inequality? Perhaps an individual can now hold a large proportion of the wealth, but without the quality/volume of ideas or capacity to use that wealth.