If you're confident a stock is going to significantly dip but regain its value later, is there ever a reason not to sell?

I own a stock, GDLC. It's an index fund built on the big crypto coins. The people that I trust are telling me that the price of crypto is going to take a big hit this year. It's definitely going to rally this year or next, but I'm going on the assumption that it's going to lose a lot of its value soon. What I find strange is that a lot of those people that are telling me the sky's about to fall, are still holding. It. I don't get that. Wouldn't the best strategy be to sell most of it off now with the understanding that you buy back in once it's gone low enough? I get those hedgeing your bets but the people that I'm talking to are pretty confident it's going to nosedive, so why even bother hedging at that point.