When you are inject 3-5 trillion dollars into the economy over the span of months, it takes a while for reality to catch up.
The best strategy then would be to know when the retirement fund money stops doing this due to age pyramid collapse i would assume.
When a buyer buys a stock, they are not giving money to the business.
Als, businesses get removed from the SP500 all the time:
https://www.bankrate.com/investing/s-p-500-stocks-list-of-ad...
They generally have to perform (profit, profit margin, revenue growth, market share growth, political influence growth, etc), and the higher the performance, the more their shares are worth (obviously).