In your opinion what are the reasons that let someone start dumping his bitcoins and walk away ?
I personally (and this is just my opinion) that it's more panic then simply his need of money or something else , as we saw on the BitcoinXT last time , people started to panic and simply sold their bitcoins and that caused a drop in the price .
I cannot say why ALL the people who dump their BTCs do so, however, the majority of them would be newbies and their unrealistic expectations. Maybe they think that as soon as they start trading their BTCs will double or triple. What they need to understand is that BTC trading is just like stock market trading. It has its ups and downs.