Yes, some working folks will be able to save if life cooperates. But most working folks not so much.
Not a flame, but an example of how it can be done. We haven't seen much of him since that thread but if true it is an example of how it can be done. Difficult? Yes. Unusual? Very much so. A pizza delivery driver within a few years of being FIRE:
http://www.early-retirement.org/for...aiming-at-fire-in-a-few-more-years-72212.html