I can say that in the December the whales withdraw a big amount from crypto market for Christmas . So market getting dump in every December also some coins are in hype because of there launchpad. Other cause may be shifting of money for one to another .
if there's one thing I noticed in this crypto market:
whales and hodl don't sell bitcoin to buy christmas stuff, they have real world money to buy christmas stuff
these guys who make Hodl or whales are making long term investments, they can only sell to buy low, but they don't sell to spend.