The "buy borrow die" strategy is a meme. It just doesn't work the way you think it works. People just repeat stuff they heard on the internet with no real understanding. It is useful to avoid paying the capital gains tax in the very short term, but is useless for periods over 4-5 years, because it loses you more money than you'd spend on taxes.
To be specific: let's say that you own $1.1B worth of stock, $1B of which is unrealized long term capital gains. If you sold it all today, you'd owe $200M. Let's say that you're 40, you spend $5M a year, and you die at 80. So, you need $200M to finance your lifestyle, and then the remainder is a part of your estate. If you just sold $240M today, you'd pay $40M in tax, and had $200M after tax cash in your checking account to spend over the next 40 years. If you instead borrow $5M a year against your stock at very attractive terms like interest rate of 5%, and no payments until your death, you'll owe $200M on interest over these 40 years. Just paying the tax would have saved you $160M! It's even worse if you get more realistic terms, because 5% rate on a personal loan is too good to be true, and you'll need to borrow even more to make the regular payments.
What about the remainder of your estate? Depending on whether you just sell as you go, or borrow to finance your spending, your estate is left with something between $500M and $800M. Guess what, now they owe estate tax, which is 40% of this sum (minus $30M exemption). Oops!
You can avoid the estate tax, though, but the kicker is that all of the ways of doing that do not allow you to step up the basis upon death: they just allow you to avoid the gift tax, but they do little to escape the capital gains income tax. No free lunch here either.