This is the best time to trade and buy more bitcoins or even ethereum
And not only these main cryptocurrencies. Some of the altcoins (I daresay, most of them) fell in price. Thus, the dip is always the best period to invest in the cryptocurrency and buy it for less.
You will experience such kind of thing in the future as well when you will notice a significant decrease in the market value of the crypto coins and that you will see the market in worst condition. At such times, the best thing to do is to stay patient and to keep a strong hold over your nerves and do nothing but holding of all the crypto coins which you have in your wallet to avoid any kind of loss.