I've yet to find anyone start a religious group and claim to have insight that ... it will occur at any other time but the one in which the author is living.
I always found this somewhat arrogant - to believe that
you and
your generation are the one that will see "the end", that
your generation specifically will not have to see death (whether that be due to 'rapture' to heaven or transfer into an early paradise) despite all the billions before you who have gone to the grave.
Even if you believe that there will come an "end" (and I do), it seems staggeringly arrogant to assume you and your generation above all others are going to be the ones to see it and to usher in the great "new world", build the foundation of the future, or whatever. The timing is God's not man's, and Jesus warned against trying to set dates or "run ahead" of God in that way, yet almost every generation of supposedly Christian leaders thinks it's "their" time.
It's also why I was never convinced by the proclaiming of the "millions now living will never die" message, as it was still being taught for decades, albeit not as explicitly as at in the Rutherford era.
The second thing that put me off believing the "any day now" hype is being aware of all the generations of previous Bible Students and JWs who have lived, grown old and died waiting with such certainty for their expected passage into the new world. In common with most of us who are or were active JWs for at least a few years, I've known elderly ones who have now been dead for 5, 10 or more years who long ago admitted to surprise at being frail, ill and at death's door when they thought they would stride into the new world while in their 20s, 30s, 40s, 50s... etc.