I might have different assumptions about the traditional 4%, which I thought was meant to be a perpetually sustainable withdrawal rate because it is presumed that you are going to be able to average at least 4% per year returns (some years higher and some years lower).  So, 4% should even work for someone who lives to  268 years old.

Some tricky parts are 1) withdrawing beyond 4% per year (and dipping into principle, and then if you end up living longer after you have depleted the principle).. 2)  NOT being able to sustain at least 4% on average returns on your investments, and if you believe that is actually happening to your investment, then you need to reduce your withdrawal rate.. most investment advisors believe 4% to be safe because they believe that they can achieve at least that level of returns in a sustainable way or 3) you have miscalculated how large of a principle that you need.. and the 4% returns is not enough (that is in the $5million $200k per annum is not enough)...

Part of the reason that you would want to error in the high side of obtaining a higher principle before your retire (or pull the fuck you lever) is to attempt to be able to account for the various unknowns, including cost of living increases that might happen or prolonged downturn in the economy that would end up reducing your returns and things like that... Of course, if you expect that you are going to die earlier than you can dip in to your principle and even completely liquidate your principle, but then yeah, you could become kind of fucked if you continue to live..