I'm by no means an expert but there could be a couple reasons:

1. Price correction - Cryptocurrency has been skyrocketing because of its press and "get rich quick" claims but it can't continue to claim purely based on hype that's the first ingredient of a delicious bubble. TBH, from a long-term perspective the adjustment isn't bad. Over a 30-day period Bitcoin is still up. But I guess if you bought at $2,800 or $3,000 then yes it could suck... I'm not an analyst so I have no idea if it'll go up again or not (I mean, I have personal opinions but I don't spread those opinions around like advice because I'm probably as clueless as the next guy).
   

2. Recent DDoS Attack on Bitfinex - Bitfinex (the largest crypto exchange) suffered a recent DDoS and it might've sent some users into panic as they couldn't access the website anymore. Others might've read about it in the news and started selling because they don't know what a DDoS really is and wanted to unload their coins before "their account got hacked and they lost all their bitcoins" (don't worry, a DDoS doesn't do that you can read more about that in my DDoS post - https://steemit.com/cryptocurrency/@thekenny/what-is-a-ddos)