Revisiting this post and catching up on the comments.
I think all the older ones begin to have doubts as they come to see they will not be among "millions now living [who] will never die". They realize all the dates that were promised to them have failed and they too, will die. Younger ones who are still blinded my still believe it will come.....eventually. Older ones who claim they still believe all that nonsense are just not telling the truth. Or they are delusional (still).