Well, I'd say using fear to avoid losses is better than fear of "wanting" to realize a nonexistent profit is. The former is money you have already, the latter is money you were "supposed" to have, so non-existent. Pretty sure you can see which is better of the two.

And as for how it impacted me, I'd say the best one was the pandemic crash? Like a few months ago I was a bit panicky with how the market was moving. I forgot whether it was 10k usd or 10k in my local currency (PHP), most likely the former but after it dropped to around that price I immediately went to sell out my Bitcoin and leave the market. Unfortunate that I didn't buy after it crashing to 4k or 5k iirc, but hey, again,  non-existent profits.