Buy borrow die also leads to massive estate taxes which is why billionaires use trusts instead. Buy borrow die is best for people with around $50 mil in assets because they dont have any estate tax.
If your stock holdings are growing faster than inflation and the interest rate at which you are borrowing, it’s an easy way to monetize unrealized gains without a taxable event. If you have a huge stock portfolio, brokers will lend you money against your stock at very low rates, a few bps above what Treasuries yield. If you have $4B of stock they might let you borrow $1B for what would be ~4-4.5% using that stock as collateral. You can theoretically take out a margin loan for up to 100% of the stock held in an account, but that’s risky due to margin calls.
The idea is to let the cost basis step up to the price of the asset at your death which will eliminate the capital gains that would’ve been owed. Then your heirs sell a portion of the stock to pay off the loan and keep the rest.
People bring up a loophole that does exist, and assume that everyone uses it. Welp, like most of these "1%" discourse, its pretty damn rare.
https://taxprofblog.aals.org/2026/06/16/fox-and-liscow-the-r...
> If buy-borrow-die were the dominant playbook, the rich would be leveraging aggressively against their ballooning portfolios. They aren’t. Borrowing against unrealized gains is, if anything, more of a middle-class habit than a billionaire one.