Another possiblity is that an institutionl (whale whatever) trader could be manipulating the market for a profit.
Have a look at the theory that USD Tether and Bitfinex are manipulating the market. It's not certain, but some decent reasoning about it is outlined
here, and it's possible that they would have more power over the market than it appears on the surface.
PLUS another say 50x that on the margin side just on the way up. Then ANOTHER 50x that on the way down margin trading.
There's a lot of discussion about the possibility of Bitcoin futures trading from major groups. If it happens, that could certainly open the gates for some pretty crazy manipulation.
Currently, it's also quite hard to get very significant margin on BTC (understandably).
If I was them, that is what I would do. Push large sums in and out just to determine how fast and how much money is actually flowing in.
Don't you think the existing statistics on volume (like on coinmarketcap) would be enough for them to analyse the market before orchestrating something like that?