The reasons for current BTC price weaknesses are interesting. Margin trading is the likely culprit.

Beginning at the beginning (by way of foreplay), missionary position explanations are here:

http://www.coindesk.com/price-bitcoin-falls-500-lowest-level-since-may/


However, the best explanation is probably that margin trading has increased significantly (BTC fire sales are taking place when leveraged traders who get it wrong are forced to close their positions rapidly)

http://www.coindesk.com/margin-trading-crash-price-bitcoin/



Longer term, if regulation clamps down on margin trading to some extent, I adhere to the Telegraphs views on the subject.

http://www.telegraph.co.uk/finance/currency/10960012/Bitcoin-price-to-hit-2000-by-end-of-the-year.html