A better reason might be that people are selling coins or using coins to buy Xmas gifts.
This sounds more plausible to me. We saw this also in the past years and I am beginning to conclude it is an annual pattern. However, this is a wrong move at this time owning to the abysmal price of Bitcoin now. Those who're selling now will probably regret it soon when price kicks in again.
Christmas and year-end parties have become a common part of the habit of selling several assets, including bitcoin and other shares, I call it "book closing celebration". Last year the price decline also looks the same regardless of what the current chart shows.
I also sell a small portion for celebratory needs, bitcoin will still be speculative in the range of $ 6-7k, I don't regret it, I need to take a vacation to prepare a new strategy.