It wasn't specifically mentioned above, as we seemed to get de-railed by the massive amount of misinformation presented as fact, but to the OP, the Trinity Study also included results from non-inflation adjusted withdrawals. If you foresee decreasing (real) expenses or have an inflation adjusted pension that kicks in or something similar, it could be interesting to look at.
Again, these are
non-inflation adjusted withdrawals. This is directly from the Trinity Study authors:
As you can see, you can reasonably plan to withdrawal more than 4% if you don't plan to adjust for inflation. Up to 7% really. However, that's not what most people refer to when referencing the Trinity Study (or the resulting 4% rule), because as you mentioned, it'd be a special case for you to be able to endure 30 years of decreasing spending power. Most people refer to the inflation adjusted withdrawals, because it makes sense to attempt to maintain your standard of living. Since inflation adjusted withdrawals are higher, they require a lower withdrawal rate.
So when anyone mentions the 4% rule, they are referring to this chart:
/\ that's where the "4% rule" comes from. At a 50/50 stock/bond ratio or higher, you have an outstanding chance to have your money last 30 years. This is how it became a "rule". However, looking at charts is no substitute for reading and understanding
the actual study and it's methodology.
On a general note, I fully agree with DoubleDown above that
every single one of you needs to understand the how and why of the safe withdrawal rate testing and how it will apply to your own situation before you stop working. If you have questions at all, I'd highly recommend that you
read the actual study. Many of you missed this apparently, plus as you can tell from some of the curt responses, we (in general) can get a little testy when someone starts claiming things that simply aren't true, especially when it comes to withdrawal rates.