$SPY I don't think the average long holder knows the importance of shorts. They are seen as the villainous losers trying to profit from their holdings. What it's most often understood is that without shorts markets tend to bubble hard and fast. There are plenty of examples, but most recently look at BTC in '17 pre-CME futures when shorting it was not straight forward and not available on many exchanges, that runaway truck to $20k and nothing to stop it. Once shorting became accessible, price discovery very, very quickly took it to $3K (presently, after >2 years since $7-8k). Markets need shorts else whatever you're holding can be cut in half. It's counter intuitive, but you can't have a healthy market w/o shorts. And the Fed's grandiose idea of using the repo market to pump $100s of billions daily worth of liquidity without calling it "QE" is taking all shorts to the cleaners and sooner or later will do the same, but more dramatically, to the longs.