Most of you understand these things, but for those of you who haven't lived through the ups and downs of the stock market, housing market, etc:
BTC don't "do" anything, only people do. If the price is dropping, that means (and can only mean) that there's someone trying to unload BTC below market price - which redefines the market price. For example, the 'mystery miner' is sitting on 49511.441 BTC; suppose he wants to cash some of that out, and puts a sell order on the dark market for 10000 BTC at $14 (even though the pride is $28). He doesn't care that it's below market; best case he makes $280k, worst case $140k.
Do you really want to sell -right- when someone (with a hell of a lot more BTC than you) is seling too? Don't forget that for every person selling BTC at a given price, there is someone out there who is happy to buy BTC at that price. You may want to consider being one of the latter rather than the former.
Finally, an awesome quote I saw elsewhere on the forum:
"Buy when there's blood in the streets, even if the blood is your own." -Baron Rothschild
(more advice here http://www.investopedia.com/articles/financial-theory/08/contrarian-investing.asp#axzz1OyivE5k2