In a bear market, you actually can't lose too much money because when the market is bad for a long time, everyone doesn't invest too much capital, and very few people borrow or use excessive leverage.

In a bull market, that's when you can lose a lot of money because of the profit effect. Everyone is afraid of making too little, so they desperately chase hot trends, and even after making a lot, they recklessly increase their positions, borrow, use credit, and leverage, ultimately losing a lot of money. Don't ask me how I know this; I've lost money that way.