I'd qualify that as when people are truly deranged, not just bullish or gloomy. $20,000 was derangement and you could see that by how rapidly it happened and how rapidly it tailed off. Same goes for the utter euphoria on r/ethtrader where triumph was unequivocally in the bag.

I'll never bother selling with the intention of buying back. I'm incapable of getting it right.