In my opinion, this big falling of Bitcoin is due to uncertainty in the markets. It will be short-lived. Long-term Bitcoin holders were taking profit. With Bitcoin at 10K and the news of the Corona virus, it created a good point for profit taking. Also, average traders/investors are simply waiting until the hysteria dies down. Why do I say this? I noticed when Bitcoin fell down to about $4100, that the stable coins like USDT were all increasing, even though they are pegged to the Dollar. For example, USDT was valued at $1.07 even though it is pegged to $1.00. So I think money was being flooded into the stable coins from Bitcoin and alt coins. It is being parked in Dollars and just waiting. This money will be coming back into Bitcoin and alt coins. What this means to me is that it is a good time to be buying.