how poor can i be and have this plan work for me and still be practical? $1 million, hundred thousand?
A person could technically execute this plan with $2,000 in an IB account.
However, during a bull market we often forget how leverage cuts both ways and increases the volatility of a portfolio. I.e. if your $1M portfolio is controlling $2M in stock through margin loans, a 20% correction costs you $400,000 instead of $200,000. If you are working with a withdraw rate in the 4-6% range, the leverage could turn what would have been a survivable correction into a Sequence of Return Risk incident. It's even worse if you get margin called on a dip and then miss the recovery the following month.
Billionaires also face such issues at their level, but they may be working with (a) very low WR's, allowing them to simply post more shares as collateral during downturns, (b) more lag time for their "wealth management" lenders to margin call them than, say, a retail investor using IB which automatically liquidates them, or (c) such rapidly appreciating stock prices that eventually their collateral would have to fall a huge amount to be margin called. Additionally, if it all went to shit, a billionaire could shift from a $100M/year lifestyle to a $10M/year lifestyle. I'm sure this would be exquisitely painful for them in their own way, but it's simply not the same risk as a middle class retiree going from a $50k income to a $20k income. When a middle class retirement portfolio gets wiped out, it means making tough decisions between buying shelter, food, and healthcare. No one has ever died, except perhaps from suicide, because they had to go from a $100M/year lifestyle to only spending $10M/year, but we do in fact live in a country where thousands of people die from poverty every single day (living in polluted or high-crime places, lack of shelter or healthy food leading to chronic conditions, lack of access to medical care and prescriptions, etc.).
In a nutshell, middle class and lower-upper-class people must constrain their risk tolerance in a way the super-rich don't have to worry about. For regular folks, losing half our portfolio at age 65 would be a disaster. For the super-rich, perhaps they sell that condo in Monaco they never visit anyway, lease a jet instead of owning it outright, and quit yachting.