Every time Bitcoin has seen a big drop, it's come back stronger and gone onto new heights. Bitcoin has currently lost almost a third of its value in a couple of days and is still going down. And it's not alone, all cryptos are taking a hit against the dollar (see the right hand side of my screenshot).
There are many reasons for this. Hard fork worries, Coinbase/ Bitfinex going down, Ddos attacks. Bitcoin has survived much worse. These ddos attacks are to drive the price down and make a profit (both on the way down and back up) for the attackers. Bitcoin has survived far worse, you should never bet against it. Now is a good time to buy.
