The article explains this, they use those unrealized gains as collateral for loans—bypassing the need to pay capital gains by actually selling the shares.
Presumably they sell stock, but any money works. It's all a gamble. If the stock tanks -- and they often do-- then it's easy to end up in bankruptcy.
But this article is all about hating on the rich and imagining that it's all perfect for them. They don't want to talk about the times when the stock falls and the once rich turn into very poor.
Remind me when that's ever been allowed to happen in the past 10 years. At the first sign of any market trouble, the default Fed response is OMO and cutting interest rates to shore up the markets. Stock prices can never fall even if the actual economy is in the shitter.
