EliteZags said:
I've pretty much accepted that the actual future market performance rate is going to have exponentially more impact on my net worth than my savings or earnings rate will ever be able to moving forward
which makes projecting decades out just a trivial fortune telling exercise
In my experience, actual savings is far more impactful on success than actual returns. Similarly, behavior management (all of the various biases we are prone to have, etc...) I believe is sometimes more impactful than actual returns. This is generally true until the magic numbers are approached at which point actual market returns and still behavior drive the boat.
The reasons actual savings is so relevant early is that it is the counterbalance to spend. The higher spend is, the lower savings are, and the higher the number you are chasing. So, a double negative impact. Conversely, lower spend, higher savings leads to a lower "number", an exponentially positive impact.
I wouldn't characterize the behavioral elements as linear or exponential. Instead they are asymmetric. There are rarely enough decisions born out of biases to smooth the impact over time. This leads to significant error term from occasional very good or bad emotional (or even irrational) decisions. With a big error term, the negatives of overconfidence on early right decisions and pain from early bad decisions, too often creates perverse dynamics in someone's attitudes toward risk and future decision making, often leading to worse outcomes.
At some point critical mass gets hit (or approached) and the savings/spending dynamic is deemphasized in the calculus of the wealth trajectory, unless hitting magic numbers greatly loosens up spend/gift/legacy desires, which can lead to a treadmill effect.