Your assets tend to become more valuable over time, which allows you to borrow more money to pay the interest and give yourself spending money.
Eg, suppose you have $10M in assets and borrow $200k against it. Next year it's worth something like $10.7M on average, you get charged something like $8k in interest, and you borrow another $200k to spend. So long as you leave enough of a buffer against volatility and the rate of growth of your assets is high enough, you can just borrow money indefinitely against appreciating assets.
People did this in the run-up to the 2008 housing crisis with homes, too. Take out a loan, cash-out refinance later when it's worth more, end up with a house you've taken more cash out of than put in.
Eg, suppose you have $10M in assets and borrow $200k against it. Next year it's worth something like $10.7M on average, you get charged something like $8k in interest, and you borrow another $200k to spend. So long as you leave enough of a buffer against volatility and the rate of growth of your assets is high enough, you can just borrow money indefinitely against appreciating assets.
People did this in the run-up to the 2008 housing crisis with homes, too. Take out a loan, cash-out refinance later when it's worth more, end up with a house you've taken more cash out of than put in.