So a Ponzi scheme pays out old investors with the proceeds of the new investors. Well, current retirees right now are benefitting from these ‘artificial injections’ into the stock market at the expense of future retirees who will be left holding the bag on depreciating assets once the fed stops the artificial injections, and asset prices go down. Moreover, when they take the additional step of removing the liquidity from the system, i.e., tightening mode, asset prices will go down even further.
Consequently, anybody who takes money out of the stock market while the fed is artificially raising asset prices is benefitting at the expense of all 401k money that is buying assets now at artificially raised prices.
In short new investors are buying assets at prices higher than they would otherwise without the Fed`s involvement in the markets.