>If you don't track your personal spending, start now. Your life is a little business. If you save 25x your annual spending and invest it properly, you can declare financial independence, withdraw 4% a year, and live off your investments FOREVER.
Factually this is not guaranteed. Highly likely, yes, but its not a "truth" so to speak. This is financial advice calibrated to historal returns. Besides that, not everyone wants to life as frugal as a homeless person for 20 years. A lot of people will regret it.