The giant balance up top is an incredible FOMO machine. In the best findom/gamification, you can increase your "score" simply by giving them more money. The volatility makes the game more difficult to predict than most free-to-play games, but the daily graphs going up so fast make it hard to resist.
My brokerage account and bank accounts also display the balance. Sometimes at the top, sometimes in the middle. It's a UI decision, more than a FOMO game. With that mindset, capitalism itself is a FOMO and the balance at the top of your head (your net worth) the FOMO machine.
