Why would you hold a stock if you think it should go down? If you think the stock is valuable but in the near term should go down, why not sell and then buy in increments as it goes down?
Because stocks have a tendency to go up even when they should be going down. And when you decide that it probably isn't going down, it will go down. Timing the market isn't a reliable way of wealth generation. Long term investing is.
Prices are heavily guided by sentiment. Nobody said sentiment HAS to be tied to the entity's fundamentals. GameStop stock moved due to sentiment external to the entity itself.
