It's clear there's a liquidity machine that provides a lot of the ongoing bid. Yesterday saw that machine overwhelmed with selling pressure. Once the last bid was taken out, you saw clearly in most alt coins that there really is no demand. They fell to almost nothing. Stops that were in place all triggered and exasperated the decline. It wasn't until the shorts bought back that it ended.
Moral of the story.. and yes that included BTC and ETH, is that there really isnt the demand you think there is. A move like that only happens when there is no bid.
This will happen in the stock market one day too. March/April will seem tame in comparison.
If using leverage, keep to short-term with tight stops. But honestly.. I wouldn't use leverage after yesterday. That was a warning shot.