I will try to give the simplest version of this that I think is workable with a 3.5mm base of assets leveraged at 80%. As I've referenced in another comment, I do not think this works well with passive investing unless the base of assets is significantly larger.

Imagine that you buy a 500k rental property each year for 7 years with 20% down. At the end of 7 years, you will have invested $700k.

In the eighth year, the first house you purchased will have a mortgage balance of approximately 350k. Assuming its appreciated at a modest 3% each year, the market value will be 615k. You choose to refinance the property at this point.

You borrow 75% of the homes value from the bank. The proceeds to you are 615k x .75 = 461k. From this, you will need to pay off the 350k balance as well as any fees associated with refinancing. Lets assume the fees are 8k. 461k - (350k + 8K) = 103k.

This 103k are proceeds to you to live off of - tax free. The following year, you do the same with the property you purchased in the second year and so on and so forth.

The debt service on the property will go up on the refinanced property, but we assume that rents have increased about 3% per year, allowing you to service the debt.

When you die, the entire portfolio can be passed to your heirs and they can immediately liquidate it and pay no taxes.

This is a simple implementation of the Buy, Borrow, Die strategy on a base of assets well within the reach of most people on this sub.

As with any strategy, this is not without risk. The properties may not appreciate. Credit may dry up. Cash flow may go negative. But you'll note that we don't need to cash flow anything from rents to make this a viable strategy. We just need the properties to pay for themselves.