Yeah... Okay but did you miss the part where I just said Blackrock is building that exact functionality for their clients? Borrowing from centralized exchanges might cost someone 10%-20% but borrowing from a Blackrock ETF will only cost the fed fund rate plus like a 1% cut for Blackrock. If the fed lowers interest rates to 0% again ETF holders will be able to borrow against their BTC for 1% or less APR.