I'm still learning about buy-borrow-die, but US estate taxes are higher than income taxes above ~$12 million, right? Much less capital gains. So buy-borrow-die would generate more taxes than buy-sell-spend?
If you do want to leave inheritance, capital gains basis is reset at death, which effectively forgives your lifetime unrealized capital gains, so you would only owe estate tax. If you sold before you died, you would still have to pay estate tax in addition to the capital gains tax.
On the off chance anyone finds this comment, I found this page with the current modification proposals helpful as well: https://crsreports.congress.gov/product/pdf/IF/IF11812?fbcli...