Yes it's a rule of thumb, it's not meant to be accurate to the day. And it assumes you're investing the savings to get average index market returns. It doesn't

Yes it's a rule of thumb, it's not meant to be accurate to the day. And it assumes you're investing the savings to get average index market returns. It doesn't matter your actual salary, if you can get by on 35% of it and save the other 65% then it's all that matters. After you've saved for 10-11 years, you'll get the 35% of your original salary you live on, in perpetuity, from what you saved earlier. Now of course it's much easier to save 65% when you're paid more than if you're paid minimum wage, but still. And you'll probably want some slack because these numbers are really the bare minimum, but that's the idea. Saving 65% of your income as a SE is really not that hard for a lot of us, even less so when you realize this is the ticket to being free within 10-15 years.