I understood your point.  Past performance is no guarantee of future results.  And I&#x27;ve seen multiple people (including MMM) make that same point in several different places; nor am I relying only on one source for advice.  (Though if you&#x27;re suggesting it has <i>no</i> predictive power for long-term averages, that&#x27;s ridiculous; it&#x27;s simply that predictions are not in any way guarantees, nor do they in any way let you time the market.)<p>But even if you don&#x27;t buy into the 4% rate, or even if you want to make a more conservative assumption, the math for an estimate still works; just use a different multiplier.  And you <i>still</i> shouldn&#x27;t treat that estimate as a guarantee.  Retirement doesn&#x27;t need to be a binary one-way process, where once you retire if you didn&#x27;t plan well enough you&#x27;re doomed.  One of the lovely advantages of retiring early is that you&#x27;re still more than capable of working <i>if you want to</i>, or doing some other kind of work.<p>Nor should you assume that because you planned for 4% (or 3%, or whatever you like), you should withdraw that much like clockwork every year.  You might plan for 4%, but then spend 2.5% because that&#x27;s what you happened to need.  And if the market happens to grow 10% in a year, great, but you shouldn&#x27;t spend 2.5x as much that year.  Whatever you don&#x27;t spend stays in place, growing your buffer even more for future downsides.  If you steal away every unexpected upside, averages stop working, and you&#x27;ll be more screwed by unexpected downsides rather than just living a little more frugally for a while.<p>Estimates are just that: estimates.  They&#x27;re useful tools for planning, not guarantees.<p>Again, see the article I linked about safety margins.  You&#x27;re talking all about all the horrible things that could happen.  So, have backup plans, and backup backup plans, and you <i>still</i> can retire before your 60s.