Another presentation of the same idea is the Networthify early retirement calculator: https://networthify.com/calculator/earlyretirement?income=50...
The behaviour of the system flips as you go from investment_income < annual_expenses to investment_income > annual_expenses , where investment_income = capital * return_on_capital . Before the transition, capital drains to zero over time, after the transition, capital grows to infinity over time. +/- the model being an crude approximation of reality.