To this day I still do not have a clear explanation for why the alts all went sky high at that time. It may have been some kind of spill over effect from btc's rise in Dec of 2017. But it was cool, it gave me a decent stash of btc. (it still doesn't wipe out the regret of having sold so many in the early days, but whatever)
I'll tell you exactly why. The whale pumpers had already started the Bitcoin bull run back in 2015/2016, but turning the corner into 2017, they needed a mega
distraction. (The theory is that whales already had insider knowledge of the coming BTC futures market launch near the end of 2017). They wanted everyone possible to sell their bitcoin
prior to the blow off top. That is how they make money, by FUDing and second-guessing everyone out of their bitcoin at all the wrong times. Also at the same time, Roger Ver and Wu were forking Bitcoin (over Segwit and the blocksize debate), and whale traders were legit attempting a
"flippening" with ETH, and trolling the shit out of the forums during all of it. ICO scams around ETH were also running rampant.
So by mysteriously pumping every other shitcoin known to man sky high, suddenly and without explanation, while at the same time selling off bitcoin, starting a flame war around SegWit and the blocksize debate, pumping a supposed ETH "flippening" with ICO scams, and shilling/pumping the new BCH fork, they were legit trying to scare all the n00bs right out of bitcoin and right into the shitcoin markets. It's clear that stirring FUD was all part of their plan. I'm guessing it worked on some people. If you remember, there was MEGA trolling and confusion going on at the time. Then they pumped Bitcoin parabolic right on the BTC futures launch in November 2017.