Bitcoin futures are just placing a bet about the future Bitcoin price.That doesn't mean that the BTC futures have any direct influence over the price.Having lots of Bitcoin shorting creates some expectations that the future Bitcoin price might be lower than the current BTC price,but that doesn't mean that those expectations will become reality.
The current BTC price drop is caused mostly by the hodlers and traders selling their BTC and taking the profits.This means that they don't think that bull run will continue towards 70K USD,so they are selling now,before the price drops.
Technically speaking you're right and agree to your statement 100%. But there's always a reason behind this flash crash. I don't believe in coincidence since this flash crash or pump always everytime a bitcoin option contracts are closed to expire.
This is just my theory and might be happening, Some group of whales bet on ETF while holding Bitcoin at the same time, They will manipulate the price of Bitcoin by giving a buy/sell pressure on exchange which will result for exchange triggering to sell-off as a reaction. They timing it so that they can gain on there ETF during its closing. Doing this kind of manipulation is safe for them since crypto exchange is not fully regulated and there's no way to verify that they are the one doing this manipulation. This is the common scenario on a volatile crypto market so no one will gonna suspect on this kind of dirty job.