A few things come to mind:
1) borrowers on btcjam and the like. The only "purpose" I can see for such sites is naked shorting. If price drops, hurrah, you win, rinse, repeat. If it goes up, just default on your loan, and you still win. This is why you should never lend out your coins; either you will lose because the value of btc goes down, or you will lose most of your deals because your borrowers will default.
2) bitstamp hacker. Havent checked yet, did the coins move?
3) All the ponzi and other scam operators. Most of them dont care about BTC, they just use it as a convenient way to conduct their scamming business. Since they obtained the BTC at virtually no cost, they will cash out regardless of price.
4) the sheep.
![](https://ip.bitcointalk.org/?u=http%3A%2F%2F3.bp.blogspot.com%2F-PzaX8hS7cNg%2FUXRIvxQdP1I%2FAAAAAAAAAG0%2F6GJJowGdk68%2Fs1600%2FCartoonVolatility.jpg&t=665&c=-nqZkeMBejvXTw)