Original thinking and therefore probably wrong, but perhaps interesting:
A more precise explanation than FOMO is that the stock market is simply a form of poker.
In poker, the cards themselves have zero value, they are simply a tool used to determine a winner.
While stocks may have some intrinsic value, it is commonly acknowledged that their value as assets is substantially lower than their stock market price. Moreover companies continue to buy their own stocks further reducing the value of stocks as assets.
Unlike the card game of poker, in stock market poker the players share the pot. This simple fact explains why there is a relentless pressure to increase the size of the pot.
In 2017 the richest 10% of Americans owned 84% of stocks. These are the major poker players. They have the resources to absorb major losses and then simply bid up the next hand.
Any small players (yes that means you and me) can easily lose their shirt in a down turn as we do not have reserve assets or other means (hedge funds) and are not able to participate in the next hand.
Many investment funds, pension funds and others fraudulently present stocks as assets and participation in the stock market as "investment".
It is the equivalent of asking that people invest in poker game by representing that the cards themselves have value. If participants in pension funds and retirement plans begin to recognize this fraud this may cause the stock market to collapse. However even this is unlikely. Poker games don't collapse, people just stop playing.
Just a thought.