Yr point is well made but so also is the response by @deeznuts It's possible to safely and privately borrow against BTC collateral by using a non KYC platform such as @@Hodl Hodl and by maintaing a very conservative LTV ratio that would keep you safe from a margin call against most conceivable flash crashes (eg it's very unlikely we would see a crash to below 30K now). Also, only borrow against a small fraction of your BTC that you can afford to lose even in the very worst event (eg only borrow against 1% of yr total).