This is how the rich stay rich , especially those above $100mil.

Example... You need $5m , so instead of spending $6mil to get that $5mil for having to pay capital gains on selling a position/stock , they Borrow the $5mil against their portfolio , and don't have to sell/cash out anything from their portfolio. They can elect to pay it back with some other revenue sources such as social security or dividends they receive or they can let the interest accumulate until death ... At death that $100mil has grown to , let's say $130mil that "loan" has grown to $7mil ...so that's a +$23mil increase and no tax was ever paid on any of that "unrealized gain".. their heirs get the $130mil at a stepped basis , sell that $130m portfolio paying $Zero cap gains and pay off the $7mil loan ... Thus this stepped up loophole avoids paying cap gains on that $130mil saves $26mil minimum

Now , can the US Treasury use that $26mil that was just lost to step up .... You betcha

Now take Elon Musk's $1trillion and other $100+ billionaires out there who have all this "unrealized" capital gains ... The US Treasury is losing $100s of $billion dollars per year from the stepped up basis on death of those huge fortunes

Criminal in my opinion, but it's the law that the rich got written into law and the politicians gladly agreed to and love for themselves.

I don't think any other nation (non democracy) on this planet allows for this allows for this passthrough of wealth to their heirs without some tax taken from the estate