Excellent topic, valuable info.
For the last several years I was active as a JW I was keenly aware of and agonized endlessly over just this dilemma. I labored internally over the exact emotional economics described in this fallacy-- though within considerably less academic parameters.
In the end I walked away, after 29 --from young adult-- years. I still mourn the loss of such a huge investment but could no longer bear using it simply to justify future investment. It's called cutting one's losses-- even after the losses have become astronomic. Sunk cost, indeed.
The subsequent emotional and psychological toll is, frankly, no less tremendous than that I suffered as the "faithful" Witness. At least now, though, I have my self-respect.
A.