I'm somewhat confused. Tell me if I have this correct. You want to borrow BTC for long-term and you have more than enough USD to outright buy the BTC which you are offering as collateral?

I don't know about anybody else, but I would happily take USD as collateral, tie the loan to BTC and once the loan is done you repay the BTC and get your cash back. Granted, I am not working with the kind of money you're looking to play with. I'm just confused how you would have a hard time finding some company or individual to do this. There's quite literally no risk, if collateral is received before filling the loan. Am I missing something?

Tying loans to USD is normally where lenders jump ship, and so maybe using that as collateral essentially does the same thing and I'm just to exhausted to do logic.