Well noted, Finkelstein.
It is my belief that as Russell began his religious studies and got exposed to the adventism of those days -- looking over the computations of Miller and his ilk, he got hooked that maybe those guys had it all figured out. He saw Miller's failed mid 1840s two dates, spotted (he thought) some flaws in Miller's ciphers and finally decided to go out on his own. Yes, he met Barbour, yada, yada. But Russell had some cash on hand, was eloquent, and charismatic -- all the tools needed to crank out some written dogma. The world at the time was ripe.
I suspect he even believed the whole thing -- till 1914 came and went.
By that time the movement was like a huge ocean liner, hard to stop or turn around. By that time there were too many of Russell's cronies, Rutherford included, who had swallowed the Koolaid and were happy just going along for the ride. Everybody at headquarters patting each other on the back. Russell drinking in the adoration -- yes, he was human. And don't forget, money from all over the world was coming in.
The rest is history.
Len