The puzzle amounts to asking ourselves what is so special about 2%? And given the inevitable large swings in market theory fads, policy fads, generational changes, etc. why is the 2% so robust?
thinking in terms of half-lives or mean lifetimes may give a better hint than the annual percentage change.
log(1/2)/log(0.98)=> ~34 years half-life
Observe that calculating in the other direction, a half-life of 30 or 40 years results in very similar 98%:
exp(ln(1/2)/30) = 0.977
exp(ln(1/2)/40) = 0.983
the constancy is just the relative insensitivity to the exact half-life, suppose the half-life models how long a horse will run after a carrot dangling from a stick mounted to its head. Some will give up earlier, some will give up later and it can easily fluctuate by 33% (30 years or 40 years), yet the annual drop-off percentage would be a similar 2%
Perhaps we should think of things that could be universal, like approximate age a person starts working, approximate age a person simply can no longer work, or how many times one can fundamentally fool a person before totally demotivating them.
suppose we assume 15 till 65 years, a ~50 year career maximum (and some effective career length in between, ended either by age related problems or disillusionment):
lets take one of many "scams" or "white lies" or whatever one wishes to call them, like pension funds, when you start working and you place money in the fund, but that money devalues, and by the time you are on your pension, the money has halved in value so to speak, suppose a rough inflation rate of 2% (whenever the nation as a whole was more productive, that productivity was printed away by the central bank issuing more money, devaluating everyone's savings). After 50 years 0.98^50 = ~0.36
At some point (and it turns out this has been going on since time immemorial) people just chug along satisfying themselves with minimum wage, because the effort for a marginal increase is not commensurate to the gains, regardless of how fast you invent new trinkets for life that do not fundamentally change our (un)happiness with the status quo.
At some point its just a constant measuring how long you can fool the population before they are too old to revolt.