I think it's interesting. Heard about it on a podcast. Spending against Bitcoin collateral allows you to avoid taxes, just like the billionaires do with their stocks.
That literally is the worst case scenario, supporting fiat to exist.
It's literally other way around.
Borrowing dollars under bitcoin collateral means shorting dollar and implements a speculative attack on dollar. It's literally how you suffocate and kill fiat faster.
Of course this assumes that borrowing protocol is trustless and self-custody without rug-pull risk.
I'm with ya on ending fiat, but most people have needs today and most counterparties won't accept bitcoin today. I'd like the savvy ones to be able to hold on to their bitcoin longer.