First, a disclaimer; I was FIRE before I ever heard of MMM. My path to FIRE was not really planned or strategic, just financial laziness on my part and good childhood training. Here's how it worked for me. I got a great education, mostly paid for by scholarships. Through a couple of unlikely events, I got a highly paid job at a megacorp and kept it for almost 20 years before being downsized. I have always lived frugally (the "childhood" part).
After a few years at the megacorp, I was maxing out my 401K and had paid off my inexpensive house. Extra money piled up in my checking accounts and I occasionally sent off a big check to Vanguard. The match in the 401k was company stock and I also got stock options and grants (bonuses in the form of stock) along the way. On the options, I would let them lie until the expiration date approached and then I would do a cashless buy and hold if they had any value. The stock split twice while I was at the company and it pays a good dividend, which I always reinvested.
So, the bottom line is that my after tax investments now yield slightly more in dividends than my frugal annual budget. Just looking at my annual income and expenses, I appear to be a normal guy living a bit above the poverty level. However, if my 14 year old car were to blow up tomorrow, no sweat! I'll just go buy another one with cash. C'est la vie!