Because most of people are stupid. Be happy from that if most of people were smart we would never do any profit.
Selling when a dump occurs is too late. In most commom case you miss the bottom and rebuy higher than you sold because for the absolute bottom is typical a very short duration. At the last big chinese drop i was unable to rebuy at 450USD at BTC-E because bots did a massive buy in and the orders were never filled, price returned back over 500 in 3 seconds.
However panickers still prefer sure loss. If there were no panic sellers there would be no profit from following pumps. Someone must pay the profit for others.
Now we have to wait until things return back to normal, its not a problem of bitcoin or altcoins, its problem of no regulation because this drop was made by insolvent exchanges (fraudulent behavior it has nothing to do with bitcoin itself, only blaming and bullshits).
Silk road 2.0 doesnt seem to be the main source of dump, 5k btc is not as much.
+1
It's going back up in no time. This lows feels like the last before a new rally begins.