I would not say he is a fool, if he got his diamonds cheap, this was a valid exit point, sellorder book was empty, price close to 100k. Well played I would say. One thing you should not forget, BTC price last year was around 50% of the actual price.
I think it's more professional if we don't call anyone involved with Diamonds a fool, even if we don't understand their decision to sell when they did. I just think name calling could be a turn off to new people entering this community.
Ok, i just wanted to say that a normal user can easily sell their coins (if he urgently needed money) placing sell orders in small portions.
This is much better than for the market strategy of the sudden dump own coins.
Every educated DMD owner must respect the market that brought him profit.
And I think that the absence of the trading culture more frightening new people than my pair of sharp words