If i'm understanding correctly you want to borrow BTC to get BTC, so lets say you do 1 Bitcoin and take out 50 million sats to give yourself breathing room with 50% LTV, if bitcoin's price doubles how are you going to acquire the bitcoin to pay off the loan? Liquidation is the only option, because very few would have bitcoin playing around or the ablity to acquire 1 bitcoin within the duration.

So you taking the risk to cook 1 BTC to save how much on taxes?

The whole point of borrowing motive is to get fiat/stablecoin because your base case is you going short the fiat, and paying back with cheaper future fiat