I'm not crazy about this advice.

If you haven't sold, you may not have realized a loss, but the value is already lost. Sometimes realizing that loss and putting the capital elsewhere (where it might make better returns) is the optimal decision.

HODLing has worked so far with Bitcoin because it has strong fundamentals, and that's reflected by the long term uptrend. It's possible the uptrend could break down and HODLers will never recover their investments.

The last two bits are contradictory. I agree about never allowing emotions to rule your trades. But if you "always go with your gut feeling" then you're acting on emotion. Sometimes, the gut feelings to panic sell or FOMO buy are the most financially devastating. I prefer a more systematic approach.